Welcome to the forum, Swizzle.
You are posing a broader question as well - when to attempt repair yourself and when to hand it over to the professionals. You've claimed for yorself some knowledge that makes this particular problem tempting to tackle. Slug is raising some concerns. You have to make a decision. I'm not going to encourage or discourage you in this specific case, but i am going to encourage to continue to enlargen your envelope, with the goal of being able to get yourself out of difficulty in more and more cases.
I've added below a section from my fieldbook for researchers in situations inwhich they have no choice - it's attempt the repair or go home. Hopefully that will orient you to whatever tasks you do take on.
Good luck with it.
We cannot have a course in mechanics here. What I can do is pass on some tips, some of which are reflected in the contents of a good repair kit, and some of which are general principles. The very first principle is that you have to do it. The piece of equipment
has stopped working, it is important to your work
, and there is no way for you to get professional service
for it. You may destroy it in the process of repairing it, but there are ways to minimize that possibility, and if you do not try, there is no chance of success. Overcome your anxiety, ask for assistance, and get to work
It is amazing how many mechanical devices stop operating from a simple lack of cleaning
. They do not really need repair, they just need the cleaning
and oiling that they should have received long before they gave up in protest. From pocket knives to electric
motors, field conditions, storage
, and neglect result in dirt and rust interfering with proper operation. When you are confronted with a failed piece of equipment
that does not have obvious damage, first search out the moving parts
. Determine whether they are indeed moving freely, and if not, either directly oil
them while moving them back and forth by hand, or disassemble, clean, and oil them.
There are only a set number of ways for something to have been assembled in the first place, so if you look carefully, you should be able to disassemble the item. Every once in awhile you will find a plastic case that is glued together, but usually there are assembly screws, set screws, or spring clips there somewhere. That, of course, makes it very important that you have the right disassembly tools, which tend to be Phillips screwdrivers, Allen (hex) wrenches, Torx wrenches, and internal and external spring clip pliers. Assembly with straight-blade screwdrivers is rare. Shaft length can be a problem. Often, assembly screws are at the bottom of deep holes in the sides of a molded case; the manufacturer saved a little bit of money
by using short screws. That means you need long shaft screwdrivers and wrenches to reach down in the holes. The screwdriver on your multitool will not do.
There are principles for disassembling an unfamiliar piece of equipment. First, have a work surface that will prevent your losing small parts. In the field, a tarp may do, but if there may be internal springs involved or spring clips, consider emptying your tent, closing yourself inside, and working where there are walls to catch flying parts. Remember that there is one type of spring clip, commonly used to hold window crank knobs in place in automobiles, that is universally called a “Jesus clip” because of the expletives used by mechanics as the little devils go flying about the garage. Along with a work surface, you need some way of containing small parts. At home, a retired cupcake baking tin does this job well, but in the field, you will have to improvise.
Systematically remove each part in turn, and lay them out on your work surface in the order and the orientation in which they return to the piece of equipment, particularly if they are parts stacked on a shaft. Consider photographing each step, or sketching the way the parts go back together. In the case of screws, group them by function. Pay particular attention to how the piece of equipment works; after all, you are looking for something that is not working as it should. Clean everything, which may include lightly sanding
parts to smooth them and remove rust, before re-assembly. If you find a broken part, it is time for you to become really creative and either repair it or make a replacement.
In any device that utilizes gas pressure, such as stoves and dart guns
, the likely source of a failure is an O-ring or flexible gasket. These little black nitrile (synthetic rubber) doughnuts seal small cracks between metal parts. It was one of them that failed in the Challenger space shuttle disaster. They wear out, or get cut. Occasionally, but only occasionally, you can make replacement gaskets out of sheet rubber or plastic. I have done it semi-successfully for a dart gun. In more demanding situations, there is no substitute for having a set of standard O-rings available as replacements
. You can buy a large set for very little money
from Harbor Freight Tools or similar cheap
tool warehouses. I recommend going into the field with two of every size in the set.
Good ol’ boys repair just about everything with duct tape. Army Rangers carry electrical
tape for the same reasons. I recommend both, plus a variety of glues, as part of a repair kit. I also recommend small quantities of sheet rubber, gasket paper, and similar materials with which to make small parts and patches.
Glues come in various forms for a reason. The things that need to be glued vary in their material, the amount of flexing in the connection, and the size of the gap to be filled. Super Glue is wonderful, but it only works on parts with no gap (like cracked plastic or porcelain) and no flex. Model airplane cement (Duco) is a rigid plastic itself, so it will fill a gap, but it is not flexible. The same is true of epoxy
glues. If you choose the two-stick, as opposed to the two-tube or two-syringe type, you can even do limited molding with epoxy
. I used it once to make a new threaded drain plug
for a sailboat by greasing the threaded hole, filling it with epoxy, and then unthreading it after it hardened. Contact cement, the super version of rubber cement, holds surfaces (such as cloth) together and has a lot of flexibility. Its limitation is that it will not bridge a gap. Finally, there is Shoe Goo. It is designed for shoe repair, obviously, but shoes present a difficult problem for an adhesive
. They involve big gaps, must be flexible, and endure a lot of stress. Shoe Goo is very flexible, and very sticky. It is almost like silicone sealant
, but much stronger and much more adhesive
. It works in the worst cases, although I recommend some coarse sewing as well if you are repairing a shoe.
Sewing may seem an obvious answer to torn cloth, and it is, but also consider gluing on a patch. There is a second sort of sewing that may be needed in field conditions. The item to be rejoined may be too tough for a needle. In that case, grasp a small nail or bit of wire in your Vise Grips or hemostat, heat it, and burn holes along both sides. Then lace the sides together with thread, fishing
line, or even wire. A broken zipper (on a day pack, in my personal experience) can be replaced by a series of ties in a similar fashion.
Well, what about everyone’s repair kit in a can, WD-40? First, it is more useful as a solvent than as a lubricant. It is wonderful for cleaning and freeing stuck parts, but it evaporates rather quickly. How quickly? Did you know that you can use it as starter fluid for diesel engines? That quickly. There is also one problem. It is usually marketed in aerosol cans, and you cannot take them on an airplane. It is available in ordinary cans, but hard to find. If you find a small can of WD-40 or the slightly more viscous 3 in 1 brand, it is not specifically banned by the TSA in checked bags, and I have successfully gotten it by them. Pack only a sealed (not yet opened the first time) container. Unfortunately, the readily available alternative to WD-40, mineral spirits or paint
thinner, is specifically banned from both checked and carry-on luggage.