Iím grabbing at straws here because I havenít done this myself to my print washers. Jobo sells a cleaner for their plastic processors (CPP-2, etc.) that does a fantastic job. You mix it in and let it work all night. Admittedly you can add heat there but it might be worth a try. They offer a 4 oz size which would make sense for you and a
4.7 pound size for frequent users of the bigger processors.

Here is what B&H says about the 4 oz size.

ďJobo Processor Clean II is a non-hazardous, environmentally safe cleaner for color
and black and white processors.
It helps to keep algae in check, along with breaking up mineral deposits that can damage the mechanical parts of your processor.
Makes 4oz of cleaning material (which you mix with a lot of water)
Mixing and application instructions are included on the package label. ď

Good luck,

John Powers