Hopcar: I took your advice and fired of a question to Jabsco (Xylem). Surprisingly, Jeff Lander, a product specialist got back to me very quickly and provided two pieces of information.
First, regarding the 15 minutes of operation and the reset switch:
It means that the pump can be run for 15 minutes safely and then should be shut-off. There is however, a poly-switch that will shut the pump off if you run it dry for a period of time or if the motor/impeller isn’t spinning freely. If there is a blockage or if the impeller is in a set position then what happens is the motor cannot spin freely. This causes the macerator to draw a large amount of current, which trips the polyswitch that turns the pump off to protect it.
This does not quite fit my problem as my pump never shuts off, it just slows to a crawl, but it is good to know.
He also responded:
From time to time the impeller can develop a “set” position. While sitting in the housing, a few of the vanes are always bent over. If the impeller isn’t in great shape or if the impeller sits for a period of time, then what can happen is that the impeller develops a “set.” The impeller “set” can sometimes causes a breaker to trip or in some instances, cause the motor to appear to run slowly (because the shaft isn’t spinning freely). Once the set is “broken” and the shaft can spin freely again, it appears as if the speed of the motor “picks-up.” If you think the macerator is running “slowly” then pop the cap off at the back of the macerator, insert a slotted screw driver and turn the shaft to aid in breaking that set position.
Again, this does not match my situation as I've had the behavior start while I was using the motor - no time for the impeller to take a set.
I guess I'm never going to know exactly what has been going on. I have removed the holding tank
and all the plumbing
. Before spring it will all be reinstalled with the motor right on top of the tank, in full view and with access to the screwdriver slot in the back of the motor. It will get annual lubrication, the lift
height will be decreased and the potential from a deck plumbing
vacuum leak eliminated. It may yet fail agian, but I will know exactly what is NOT causing the problem.
Thanks to all the members in this list for your help.