While at Carlisle, I discovered that my tach stopped working when the lights were turned on.....Not a large problem, but a pain in the &*#$.....I spent today chasing the problem, and it turned out to be an internal ground failure within the tach......It would back feed thru the dash lights until power was applied......Running a new ground lead from the case seems to be the fix.....Hope this helps someone else some time....
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