Instrument cluster/board turn signal problem

[researchguy]

Hi,

I do have a couple of frustrating problems with my 1992 500SL. I'm hoping you might be able to direct me to some less expensve fixes.

1. The rear corner plastic windows in the soft top are cracked, and about five inches of sewing on the main rear window also needs to be redone. I have gotten an estimate of $650 to do all this. This seems excessive for what must be $10-$20 worth of thick clear plastic and a couple of hours' worth of sewing. Has anyone found a place that sells suitable thick, clear, sewable plastic and thick, heavy thread so I can do this job myself? Would sail thread work? Is there anything really special about the plastic? What thickness is it? I don't even know what to ask for.

2. About a month ago, all the indicator lights started coming on whenever I used the turn signal (as if I was starting the car). When the left signal is on, the fuel gauge goes to zero, then back on, sort of in time with the flashers. A mechanic I trust (not at a MB dealer) has determined that the problem is in the circuit board behind the instrument cluster. But, even used, the going price for that entire unit (cluster AND board) is about $600. Is there any alternative to replacing the entire unit? How could I find a shop that would do board-level troubleshooting and repair? No car mechanic seems to do that.

I'm in Austin, Texas, but would gladly drive a fair distance to get these two problems taken care of for less than $1250 (plus labor to R&R the instrument cluster -- money I already owe). Or ship the cluster and work with someone remotely.