My 14 year old GE fridge is still working fine... except half of the time when the compressor cycles off it makes a horrific clunk/bang kind of sound. The other half of the time it shuts off quietly. It starts and runs quietly all the time and the fridge works fine otherwise. The clunk sounds like if you pick up a compressor and jiggle it and it bangs on the housing, but much louder, I guess, since the internals are moving pretty fast. What could be causing this in an operational compressor? Is it a sign of imminent failure?