One thing that I've found about working on them is that it's necessary to replace the float every time I rebuild one. Those plastic floats have a nasty habit of soaking up fuel and getting so heavy they can't produce enough lift to effectively shut off the incoming pressure. Another trouble spot is the riveted-in plugs at the bottom of the float chamber. They get loose and leak, emptying the float chamber as the vehicle sits overnight. I like to peen the plugs tight with a small ball-peen hammer, then use a fuel-resistant epoxy over them to assure there's no problem with future leaks. The plugs are supposed to be in a "dry" area, so if the leaks can be stopped, the epoxy doesn't deteriorate from being submerged in gasoline. That plastic cover over the float pivot could have been scavenged from a junk carburetor, but it's not likely an aftermarket supplier would be able to find a replacement. I don't think I've ever seen a broken one, in 40-something years of fixing Q-jets.
Jerry
