If your gun is one made by Miroku, here is a site that might help: http://www.wisnersinc.com/additionalinfo/Mirokusprings.html
They don't claim to offer repair services but you could e-mail them and possibly get pointed in the right direction. The way your question is worded it makes me think you may have a single trigger that is not setting up for the second shot, rather than "not cocking". If my guess is correct, it might just be the inertia mechanism is gummy and sticking.

> Jim Legg <