Hm. Did you remove the mainspring at all? I have caused this problem in a rifle by putting a pre-load washer on the spring guide end of the spring, so the sear cannot engage the bent.

I will have a look at the Chambers diag and see if there is an 'obvious answer'. Nice accurate little rifles the Paras.

Blimey, thats a bit complex. Can't help you.

here is the diagram

http://www.gunspares.co.uk/showcatimage.asp?id=24271