For any game with the 7-opto PCB troughs, you need WMS kit # A-18244, which replaces the PCBs with new boards, and rubber shock mounts.
This kit, of course, has been NLA for 15+ years.
Great Lakes Modular, however, makes nice new PCBs that replace this kit, and are basically foolproof.
Depending on the condition of your connectors, you might have to replace the plugs if they're worn out.