The mainspring on these guns has a plastic "yoke" on the end that tends to deteriorate with time. If you take the grips off, cock the hammer, and put a paperclip through the hole in the end of the mainspring guide, you can then pull the trigger and remove the mainspring. If the plastic is cracked, you have a weakened hammer fall. Replace the mainspring. The complete assembly is available from Numrich (
www.e-gunparts.com).
Bill Jacobs
Bolt&Barrel Gunsmithing, LLC
www.boltandbarrel.com