Musky said he thought this had been approached before . I did a search and could not find this exact problem, so here goes.
All of a sudden after many years my carby started gushing after tickling for a cold start. Upon removing carb cover (Amal 389),
discovered that half way up inside of the float bowl, on the backside wall, IE: the round barrel of the main jet tube that comes into the float bowl, had a casting burr on the wall from day one, where the casting leg had been broken off after it was no longer needed. Well this small imperfection (burr) had raised just enough of a burr smack in the center of the backside of the float, so when the spacer was put in to keep the float from sticking on the cover, it moved it just far enough back so the two burrs would make contact and stick the float in the down position and flood everything. Cleaned up burr on float with fine wet and dry paper, cleaned off burr on casting with really fine points type of file, and WELLA no more flooding. It took many years for the casting burr to create a float burr, that would jam the float in the down position. Long story short anything can happen and will eventually ! !
