I bought a dog of a Pro Target second-hand recently, which has been plauged by all kinds of problems. I've sent it back to air arms for a service to fix the leaky reg etc. and I thought they'd fixed the cocking (seemed ok at first). Took it to the club this morning, and it was back to its old ways; really stiff to cock and requiring a good hard yank to stand any chance of cocking it.

I've done a few searches on here, and it seems the problem is quite common. The trigger follow through travel adjustment wasn't the culprit (wound out enough) and I couldn't find a problem with the sears engaging (it would cock when the case was off and when I was pressing down on the big cocking arm to keep it in place). And then I realised it might be the cocking arm "slipping" if you catch my drift. I placed a washer under the brass shim and it now seems to cock fine now (fingers crossed).

Now here come the questions (as usual):

1. Would placing a washer underneath cause any harm/stress on anything?

2. Anybody had any similar problem?

There's a (rather poorly annotated ) pic here and thankyou to whoever I nicked that photo from