There are other manufacturers of sailboat hydraulics, so it might be worth talking to them, in order to get some more information/gain some insight.
Also, were it me, I'd also post this over on Sailing Anarchy Forums
given that there are a Lof of racers there, with plenty of experience with both Navtec, & Hydraulics. Including sailboat hydraulics of other makes.Plus, there may be some resources on www.L-36.com
And it couldn't hurt to contact some of the bigger rig shops in the US either. For more info, possibly parts
, & if you're lucky, the POC for a local who can fix it for you.
& Hydraulics comes to mind, but I'm a bit under-caffeinated at the moment. So the name may be a touch off. But there are some Huge rigging
outfits in FL, so it's worth a shot.
In the meantime, in order to keep the boom from being a head knocker, you can take a block of softwood. As in only one notch more dent resistant than Balsa. And drill it, longitudinally, so that the hole's slightly bigger than your vang's piston. Then saw it down the middle, & put it in place with a couple of lashings.
Just be sure to clean both the block & the cylinder ever day or three, Religiously. So as not to score the piston. Thus screwing things up royally.
Ah, & put a bevel/recess on the ends of the inside of the hole. So that where it meets the vang's cylinder, naught comes anywhere close to kissing any seals
or vital bits.
Or, a better option, is to simply beef up your lazy jacks so that they're strong enough to support the; boom, the sail, & a couple of people hanging on same.
That, or an old fashioned topping lift
PS: If you go with the block for the lower end of the vang's piston, you might also cut some flutes on it's inside, longitudinally, so as to give what grime does get in there, a way to flow out. In between cleanings that is.