In electromechanical games, the bakelite spacers in all the switch stacks
dry out after many years and the entire switch stack may become loose.
Before adjusting the switches be sure to tighten up any loose switch stack
screws. You may need to get some itty-bitty screwdrivers to handle these
small screws. After these are tightened then your adjusting of the switches
will last longer and be more reliable.