The original instrument cluster clock setting switch failed, so I purchased a used 500SL cluster thinking they were interchangable. Turns out they aren't, speedometer calibration way off. Then I moved the clock setting switch to my original PC board, successfully, but broke a couple of ribbon cable connections in the process. Repairing the ribbon cables turned out to be a tail chase. Repair one and two fail. Now it's working, but I feel that the PC board is like a bomb waiting to go off.

That's why I'm trying to replace it.