Got an old model 45 and did a lube tune. Shot it a bit and all was well. Now, it refuses to fire. I can cock it, holding the barrel in broke position and release the trigger only while holding the barrel tightly. Any ideas???

The only thing I can think of is the little spring at the front of the trigger assembly. It pushes the latch up into the slot in the piston to hold it back. If it were mine I'd take the action out of the stock and check.