I recently received a D1 "Chairmen" ,I don't know the year of the system but has to be at least 10 years old. All appears to be working fine except the Temp won't go below 100F and it won't allow you to dial the temp down at all. I can raise the Temp from 100F upto 104F but it won't let me go back down again. . I know the tub has been disconnected (power) for a few days. I had been told about this problem prior to getting the tub, but hoped the system would reboot and clear the issue. Does this sound more like a board issue? Or a broken "down" button on the control panel?