check the trigger .
make sure it isnt up in the sear hole . if it is , it will not alow the sear to drop for the full cock notch .
then i would look at the inside of the lock inlet . if fouling was getting down behind the lock , then i would suspect that the lock was not inlet deep enough to seal to the barrel flat . when you took the lock out and re installed it , you may have cocked the lock alittle more . thus causing the sear to rub and catch so as to hold the sear out of the full cock
i would agree with the others here , definatly a clearance issue