Just a thought… the hammer screw is slightly buggered suggesting the hammer may have been removed. Start with the hammer in the full cock position as your photo shows. If you can remove the screw and the hammer, rotate the hammer back 1/4 turn from where it was mounted , put it back on the square tumbler stud, put the screw back and try it. Quite possible may have been reassembled wrong after cleaning. Hopefully it may just work perfectly .Best of luck.
Snoot
