I've got the "bouncing tachometer problem" that has been reported elsewhere in this forum (i.e. the yips). The tach and the oil pressure guage intermittently and simultaneously drop to zero for awhile and then back to normal for awhile.

This is a known problem in the 140 chassis. Technical service bulletin of 4/28/97 recommends replacement of the electronic circuit board of the instrument cluster when the intermittent tach/oil pressure guage problem is present.

However, the instrument cluster is a $1400 item and ought to be a testable/repairable item. The circuit board is loaded with test connectors--as if the board is capable of being plugged into a testing device.

Does anyone know of anyone who tests/repairs MB instrument clusters?

Something is common between the tach and the oil pressure gauage--but can't figure out what. All other gauges acting normally. Just those two bounce--and they bounce in sync with each other. I've studied the wiring diagrams and can't identify any input common to the tach and oil pressure guage. I've cleaned the ground involved (W1; behind instrument cluster) since that is a common link. Problem persists--so I figure it must be internal to the instrument cluster.