Help! - Marlin model 60 trigger or firing pin not resetting

Feed and extract seem OK, but about 30% of shots the trigger pull does not cause anything to happen. Pulling the bolt handle back an inch or so seems to reset it, so I can take a shot without feeding a new round into the chamber.

I have cleaned it pretty well, I think.

I have tried a dozen types of ammo.

Suggestions, please?

trigger reset spring, located in the trigger assy., only , may be weak, or out of place a bit. pull the trigger assy off of the bottom, turn it over , and check it out. also make sure the top of the trigger looks fine, and is not all jacked up...

How far are you taking it down to clean it? If you haven't taken the bolt and trigger group out here are some "how to do it" pages:
http://www.castbullet.com/misc/m60.htm
http://www.survivalprimer.com/PaulsGuns/22lr_marlin_model_60_22_cal.htm
http://www.thehighroad.org/showthread.php?threadid=86314
I suspect the disconnector (http://www.rimfirecentral.com/forums/showpost.php?p=1101642&postcount=6) is not resetting correctly. Check that it is not dirty and sticking (http://www.rimfirecentral.com/forums/showthread.php?t=153796&highlight=disconnector). Check the disconnector spring (http://www.rimfirecentral.com/forums/showthread.php?t=153796&highlight=disconnector) as well.
Trigger group dis-assembly/assembly: http://www.rimfirecentral.com/forums/showthread.php?t=197703
There may be more threads of interest here (http://www.rimfirecentral.com/forums/search.php?searchid=1415222).

This thread (http://www.rimfirecentral.com/forums/showthread.php?t=143780) on improving the trigger is worth a look when you get the time.

Regards,
Greg