We've done this mod many times and always use cyanoacrylate. If used properly it should not be a problem. Perhaps some glue worked its way onto the contacts? If this is the case he might have used too much glue. Without some form of adhesive, we've found that the board tends to not stay in proper position.
As for the encoder, it's quite possible to remove it from the board without damaging either one. I've done about 5 of them and the encoders have always come off unharmed.
Stu
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If you want it to break, buy Sony!