I'm not familiar with the 955, but looking at the parts diagram, could be simply a snapped/broken cable. Disconnect cable from back of tach, start engine, and verify cable turns. If it does, probably bad tach. Bob
Here's the parts diagram and replacement cable #11 is part no. LVU804125 for $31 USD:
Hope that its the cable as the Tach is exspensive.
Cable sometimes comes loose from the back of the pump where it connects to engine.
When they break its in the low spot where moisture will sit right about the middle.
If/when ...replaceing....tape the new one to the old one .
This lets you pull the new one through all the mess between dash and engine...its a tight fit.
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