By any chance do you have an amp meter? It sounds like the compressor is definately locked up. The meter will show a constant high locked rotor amps, LRA, instead of high amps and then it would drop to low amps, your running amps, RLA or FLA.
Is a 3-1 the same as a hard start kit? I used one on a stubourn compressor once and it ran fine, but I would also agree that it may be time for a new compressor. It sounds like it is dead or dying.
By the way I never used the hammer trick, but I do remember one teacher talking about it to free up a compressor. I always thought that sounded crazy, but it makes sense.