My favorite LGS has a used 65-4 that functions fine if held muzzle down, but. The cylinder will not turn if the gun is held level or barrel up. I held the thumb latch back, opened the cylinder, and cocked it several times. The hand does not rotate the cylinder. This is a LE trade-in, no box, worn rubber stocks, at $289.99. Can anyone tell me what could be wrong with it, and what it would take to repair it. Thank you.