Dehumidifier problem

My dehumidifier does a good job of extracting water. My problem is that it does not automatically turn "on" or "off". Rather, once I turn it on, it does not turn off until the bucket is full and the "full bucket" switch causes the unit to turn off due to the weight of the water. When I remove and empty the bucket, the unit comes back on until the bucket is full again. This is the case regardless of whether the control knob is at the lowest or highest setting.

My first thought was that the humidistat is bad; however, I am told that the part is no longer made. Does anyone have any thoughts on the cause of my problem? If it is the humidistat, can it be repaired or, if not, where can I get a new or used one? Or, am I just out of luck?

Thanks very much