Had this happen on another guys couple weeks ago.
Loosen the screw opposite the lock.Tap screw to push off lock.Scrub lock with soapy water and rinse.Lay on cookie sheet in oven on 175 for about 1/2hr to dry.Light coat of lube and replace lock.
First, loosen the lock screws a bit until the lock is still firmly in place, but not cranked down. Try it then. If that doesn't work, take the lock off and see if the hammer falls when you push the sear arm. (Watch your fingers.) If it falls, then there is contact with the stock. You'll need to identify where and remove wood. If that doesn't work, you can try cleaning and oiling. If it's still not dropping, I suspect the tumbler notches and/or nose of the sear may need to be reworked by a gunsmith.