The threads on the float bowl top seem to be worn out. When I tighten it up, it seems OK, but then when I tighten the banjo nut, it pops loose. Functionally that isn't too bad, but I would rather have it work as designed. The banjo just misses the tickler button, so that isn't the issue. My first reaction is to replace the float bowl and top, but that is a fair amount of money. How likely is it that just a new top and a PR6AQ washer would cure this ill? The threads all look fine now, so there isn't an obvious choice between a new bowl or top.