Turned tach knob 180 degrees and back to clean contacts, now reading is way off

[BassManGuy]

My tach always was a little jumpy, and it isn't the voltage regulator or anything because I had it checked out. The setting it was on was 6. I turned the screw adjustment 180 degrees clockwise and back. Then I did the same thing counterclockwise and back. The arrow is pointing at 6. Now in idle. it is reading about 1200 rpms which it is not really idling that high. The needle doesn't move or jump anymore, but the reading is off. When I go to get on plane, the needle moves past 8000 rpms where it can't move anymore. Did I do something wrong?

[Charles Prestridge]

I would wiggle it just a little and see if you can get it to read correctly. It may help to have someone looking at the tach (with the engine running) while you wiggle it.

That worked for me.

Good luck

[Charlie206]

Some tachs require that you depress that knob a little. So depress it and spin it, not 180, just spin it back and forth between the lowest and highest number several times, then land it on 6.