Actually I think the Progressive HW50C may be the only one that can be repaired
and I have heard of them sending free replacement parts .
I installed mine myself just after the elect power reel .
With the same fear of being with out power if something went wrong I wired it
with receptacles and plugs so I can unplug it and bypass it all together .
Its been several yrs now and I have never needed to do that .
It has a remote panel that reads the volts and amps on each leg that is
very handy . I mounted it in the bay with my power cord so I can see if
the power is ok before closing the door.
Progressive HW50C is my recommendation .