I don't remember whether the casing of the encoder was such that it could be disassembled from above without desoldering it. My recollection is that no, you'd have to desolder it to get it off of the board at all to even get to the point where you might be able to even attempt disassembly.

Then there's the issue of... by disassembling it you might ruin it beyond repair...

And as Rob said, and I painfully discovered... getting the encoder off without destroying it and the PCB is nearly impossible. You're much safer just clipping the thing off and putting a new one on.