Gene,
I have the same problem with my Whirpool TU8003XLP0 compactor. When the ram goes down, the unit fails to sense when the bottom or sufficient trash resistance is reached. The ensuing banging lasts for 5 seconds (unit shuts off) or less if the key is turned off. When the unit comes back (turned back on), the ram retracts normally to the top. This occurs wheter in normal or solid pack mode and the compactor is empty. Took apart and it looked like there where shavings around the power nuts. Possibly stripped and not holding. Does the unit sense pressure and needs the nuts to hold for that?
Thanks, W