Re: trigger trouble
First of all, Welcome to the forum!
There is a piece that is called the sear, that is the piece that catches the hammer/striker when the gun is cocked. It is possible for this piece to get rounded or perhaps the hammer/striker has been damaged/rounded.
As for the issue with a spring possibly being lost, I'm not sure. I'm out of town right now and cannot look at one of mine. If you push down on the sear and it pops back up, I would say everything is there, but without looking at one of mine, I'm not 100% sure. I get home tomorrow night and if someone else has not helped and solved your issue, I will be sure to break out one of my frames and try to help you out.