I have a old Colt SP1 that I last shot in 1980. I cleaned/lubed it with CLP and take it to the range. I put 5 rounds in the mag and shoot. The first shot fires and is ejected. The next round is chambered but when I pull the trigger, the hammer does not move. I open the gun and see that the hammer is pulled back. If I move the safety a little, the hammer goes forward a little and then the trigger can engage the hammer.

I tried the gun again. Fire one round and the gun cycles but the trigger does not engage the hammer. I wiggle the safety and now the trigger can engage the hammer. I shoot 40 rounds and the gun seems to function without needing the safety wiggle. However, once in a while (every 20 rounds or so), I need to do the safety wiggle to get the gun to fire. I looked at the lower receiver parts and the buffer tube and everything looks fine. Any ideas on what could be causing the problem?

take it to a pro

Did ya try looking up the problem in the -23&P? (old.ar15.com/books) or post this in the Troubleshooting section? (where Tweak - our resident AR repair expert - resides).

I had the same problem with my Bushmaster once, and it was as rn45 said, blown out primer crap got into trigger, just cleaned it up and it worked fine afterwards.