I never removed any of the circuit boards from the assembly. I resoldered all the pins and the seam where the boards come together, then I sprayed the contacts on those relays with electrical contact cleaner. I would not want to take that assembly apart if I absolutely did not have to. I think you would have to unsolder every pin and then try to reassemble and resolder all of those. That would be more than I have the skills to try.
I was told by a very reliable MB tech that the boards fail mostly with cracked solder joints at those pins. I got a magnifying lense out and looked at them very closely. Almost half of them had tiny cracks around the pins. I think that is where they fail.