Due to a recent windfall, I decided to have the original Tachometer on my 1983 r 65 LS rebuilt. When the rebuilt Tacho arrived I removed the old style (with the red over rev light) tacho I had been running and installed the original only to find the main instrument illumination not working. The neutral, generator, oil pressure and high beam lights all worked. As per Snowbums schematic I checked the voltage from the pins to the main light and it was live. I also checked the bulb and it was good I have returned the tacho to the rebuilder for checking.
When I replaced the previous tacho, the same thing occurred (No main instrument light (which had previously worked) ! In addition the rev counter only works when the ignition switch is in the run position and not in any other position. I have the Euro style ignition with : Off, Park light, Start/run, run/park light and run/headlight! Neither the ignition switch or the tacho were messed with nor was the white plug in the back. Any ideas about what is going on??? Any and all help/ideas appreciated.