My CP31 has a flaky digital thermostat. I replaced it with an analog thermostat bought online that was originally prototyped and made to control house furnace fan run times.
I now run my bath 1 as a pre wet, and run the OEM analog thermostat controlled tank 2 as the developer, and tank 3 analog oem thermostat as bleach/fix.

I have gradually been replacing the electrolytic capacitors in mine. The W/D moduel when flaky first, and new capacitors worth perhaps $8 brought ti back to working fine.

I have replaced the soldered on battery on the main board of the processor witha ni-cad from a portable telephone, when the old one would not remeber the speed I had set it to, etc.
I am holidaying now until 18 July. PM me if you can wait a while for more detials. I have 4 spare analog furnace thermometers and the notes of when I replaced mine around the house somewhere.