Panel lamps out - fuse OK

I have no panel lamps on my 1975 Scamp. The fuse to the circuit is OK. The shifter,ash tray,radio, and heater control lamps are OK and dim properly with the dimmer on the headlight switch. The service manual shows a connector with ground and + coming from the ash tray light up to the round cluster connector, through 2 cables/connectors. One of these may be disconnected - I'll check when I find them, but here's the question: Is there any component (resistor, transformer, regulator, etc..) on the cluster PCB in the lamp circuit that might have failed? I see no schematic of the actual cluster in the service manual and nothing in the wiring diagram that would indicate there's something there, but I thought the A-Body experts here would know for sure!! Thanks in advance!!