I have 3 complete working head/controller systems and 4 power modules. I plan on re-building one of the power modules and if all goes well, to do a second one or perhaps a third also.
The D5500 controllers have about twice as many parts, including some ePROMs that are unique to the D5500. So, a similar re-building approach for the controllers is not practical. Fortunately, I have 3 controllers that seem to be in good working condition. Since the controllers can easily be swapped from one enlarger to the next, only one working controller is needed anyway. Whereas it takes from 15 to 20 minutes to swap out the power module.