SL/R129: 91 SL 300 instrument panel help
I had that trouble with my clock as well, but if you pull out the control, turn AND hold for a few seconds the clock starts to turn... because it's electric. If you tried that and it still doesn't work it could be.... expensive?
Adjust the steering wheel so that it's as far away as possible, remove 3 or 4 connectors and it's out. You can then replace any bulbs which have failed - there's 19 of them in there covering the whole panel, so while it's out, it's worth replacing any that have failed or look blackened inside. They are colour coded according to lamp wattage and you can get them from your dealer.



