Bad sockets are very common. Both wedge and bayonete sockets can crap out. If the lights are in a circuit board under the PF (like the light boards on WMS/Bally games), the solder joints joining the board to the header frequently crack as well (the inserts for those light boards also crap out, just like other wedge sockets, and some of the repro ones don't fit wms/bally machines without modification).