Ummm... some advise replacing the seat along with the needle as they both ware together.
Is it the clip or its seat that is worn? ... If your have put in new clips and they are dropping out then I'd be looking at
1) the seat ... means you need a new piston $$ ...
2) the clip ... you certain you are gettting the correct clip?
... good puzzle ... may be the best place is the airhead list for this. Good Luck.