I think it's a diode because only two terminals appear to be used. I have photos of a driver board from a punch 30 and the module has a circuit with components marked 8A K. 8A is likely the significant part of the mark.
i will try to re-build this board (print new board) with a new parts...I don't know.
I don't know how much you've worked with these old boards but from my experience, if something is not absolutely defective, you don't do anything with it. The act of soldering on these can make them unusable without a LOT of work.