I have an old Fender deluxe 900. After playing thru it for about 1/2 hour, it will start putting out a rapid clicking sound. If I bang on the top right (over the effects board) it will sometimes start working again, but not always. I have taken it apart, and i find if I unplug and replug one of the harnesses in the effects board it seems to fix the problem for a few hours. I don't see any signs of a bad plug or pins or any obvious problems. Is this something that can even be fixed?