Unscrew and remove the heatsink from the old hashing PCB, then attach the heatsink to the new PCB with thermo paste. Slide these baby into the slot and use the same control PCB and the bottom power management PCB.
Currently, no news on spar parts purchase possibilities.
Can you tell us about the controller? Will the factory S2 controller work for the upgrade, and will you have controllers available for anyone who has some that are faulty?