i have a 1960 second variation detective special..............i had purchased from a family friend a few years back! i have fired aprox. 500rd threw it since i got it with no problems at all!!! i went this weekend to shoot it and for some reason when i just pull the trigger without cocking it sometimes the hammer only goes half way back and when it falls it will not fire the round!!!! but it will fire every time if i cock it 1st!!! i noticed about 3 rounds out of the whole cylinder will fire on average and the rest remain untouched if im just pulling the trigger? (due to the cocking issue) any insight or ideas would be appreciated!!!!!! i dont just want to walk into the gun smith without knowing what im looking for and sound like an idiot!!!! THANK YOU!!!!!!