Pro-1 Problem

[Kevin Lightner]

On really bad units, I've resorted to even desoldering and removing the
keyboard buss bars completely and either use a very gnarly solvent  (like
MEK or Trichlorethane 1,1,1) OR in VERY bad cases, take a piece of
scotchbrite scouring pad and draw the buss bar through it... ONCE. (You
want to try and keep the gold plating on the bar!)

This always works for me.]

The separate J wires or springs can be cleaned in similar way, but you have
to be super careful not to bend or damage them.

My two cents....

Kevin