129/ 140 cluster question

[zhandax]

I have a W129 (93 300SL) which should be delivered tomorrow. The PO stated that the cluster died and he replaced it with one from a 140; since the mileage on the new cluster was ~30k miles below the old one, on advice here (as well as intuition), I asked for the original cluster instead.

I understand that the circuit board on these early (wheel odometer) clusters have a tendency to go bad and that the popular options are replace or send out for rebuild.

I have a chip programmer which will accommodate most programmable chips with the right pin adapter as well as a solder/ desolder station. The PO said the dealer told him there was a chip in the cluster that died from leaving the battery disconnected for a prolonged period.

Does anyone know the most common failure points on these circuit boards? I have already seen the post on replacing the capacitor (475Ω?) on the board and will do that automatically. I also plan to replace all the fuses and check the voltages at the connector pins, but there seem to be enough SL posts about dead clusters traceable to a bad circuit board to sound like a not-uncommon failure.

Do the members who have solved their own dead cluster issues find that it is mostly traceable to the capacitor, the solder joints, the traces, or is there a chip which can actually loose its programming?