I installed a p90 and a humbucker (2 wire) the 90 is fine the rest of the post refers to the HB.
It didn't work from day 1. I wired it direct to the jack nothing , took it to my local guitar tech who put it on a meter, nothing. Returned it and the the guy could not find anything wrong with it, sent it back to me I installed it and it worked perfectly, but then after a few days it cut out but worked again after about 2 minutes and the same again a few days later. A replacement was promptly dispatched to me.
This one worked fine....until yesterday couldn't get a thing out of it. I have spent the last 2-3 hours re-wiring, wiring it up direct to the jack, checking the selector switch still nothing. I even changed the the point where the earth is soldered. I had it out and wired it to the selector switch and it worked, there was a screw on the back of the pup and I could hear it moving about through my amp (it was one of the surrounds that got picked up by the magnets)
Put it back in ........nothing.
I had a cheap Hb which I have put it the guitar and it works fine.
The pickup is a Zebra type but I put a gold cover on it and I changed the pole pieces to gold as well, and the surround is a metal gold one
I am out of options, apart from getting another replacement or if you guys can come up with something.