RepairPal Certified shops can diagnose and repair your 1991 Mercedes-Benz 300SL. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
You would need to remove the dash covers and instrument cluster. You should be able to access the bulb from behind instrument cluster (a cover or two may have to be removed from the rear of the cluster to gain access to the circuit board).