Anyone ever rebuild a pressure washer pump?

What is it doing? pull the trigger and nothing? Then sometimes it does work? Hold the trigger & it sometimes after not working comes alive. If so that's the unloader that AJ mentioned.... Leave most of the pump alone, pull the unloader & polish it with a fine scotchbrite pad...

"Not supposed to let it run more than 30 seconds without pulling the trigger..." BS... The unloader allows the pump to bypass, not a big deal...

I try to blow all the water out of the pump when storing my unit & I spray WD-40 into the inlet & with the ignition off I pull the starter rope a few times...

My current unit is 12 years old.. My last one was a cheap unit & lasted 25 years...