Is the compressor running for a period and then shut down on thermo-overload? If so, for how long? Like Jim asked, are you getting any cooling at all in the water bath? The compressor requires a full charge of freon to cool the bath as well as itself.
If the unit runs and runs, because of a low freon charge, the compressor will over heat and shut down on overload. Check to make sure the condenser coil is clean and the fan is running. This will also make the compressor over heat and shut down. One more thing, check your wiring. Over the years wires become brittle and weak increasing the amp draw. This can also cause a problem.
Jim, any other ideas?
Eric