tonearm rewire

I'm helping a buddy fix a Kenwood 2055 that was given to him. I believe that it has a stock arm, but am not sure. The arm is metal, with a 'S' curve and a removable head shell. The left channel wiring is messed up. When I checked the continuity, the left signal wire was fine, but the left earth wire was not. In fact, there's continuity between the left earth pin at the head shell and the left signal wire. I've isolated the wiring problem to the arm itself, but can't figure out how to access the wires where they connect to the contact pins inside the arm. There's a small pad inside the tonearm with four pins/contacts for the head shell. I'm thinking that if it is possible to remove this pad from the arm, then I can check the wiring there. There is a small screw on the underside of the arm near the head shell attachment. I removed the screw, but was unable to free the contact pins. I read on another site that Kenwood filled their arms with foam, which would make rewiring/repair extremely difficult/impossible. Does anyone have any experience repairing/rewiring this arm and how can I repair this problem?