I removed the instrument cluster in my 1987 300E to see if I could fix a broken odometer and trip odometer (they both stopped working suddenly). Not only did I not fix them, but I managed to create some new problems with various gauges:

1. the right turn signal flasher does not come on (the outside signals flash, but not the flasher on the dash). the left flasher works fine.
2. the oil pressure gauge does not work (it is at zero). BUT if the cluster is jiggled just the right way, it will work for a split second. Or if the cluster is held a certan way (removed from the dash, moving it around to try to get it to work), it will work but will stop when the cluster is repositioned.
3. the tachometer will not go above about 1000 rpm. BUT exact same thing as the oil pressure gauge, it will work for a moment if jiggled right and will work if held in a certain position.
4. when the cluster is held so that the oil pressure and tach work as described above, if I turn on the right turn signal, check this out: the oil pressure gauge and tach needed get blipped up and down like a metronome just like the turn signal flasher should be coming on and off (the turn signal flasher still doesn't work when this happens).

There must be some issue with some of the wiring coming out the back of the cluster but I can't figure it out. I seem to have everything plugged back in the right way, and I can only get the tach/oil pressure gauge to work by trial and error, moving and twisting the cluster around, and I can't seem to figure out which of the connections/wires are the ones that are causing these problems. Can anybody help out? Do these items have a common ground, or common connector at the back of the dash? This is driving me nuts. Thanks for any help.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car