Noisy Speedometer tach recalibrate?

[spock2001us]

Speedo/tach makes a buzzing noise when accelerating....comes and goes and it is loud like gears turning...quiets down at cruising speed, so maybe it is the tach. I took the speedo apart and oiled the odometer gears, (only gears I could see) but that was no help. Now I put everything back together and my tach now idles at 400 instead of its usual 650. Is there a way to recalibrate the tach and what do I do to stop the buzzing sound?

 

[Chythar]

Is the buzzing from the speedo? I've heard of a buzzing from the speakers on acceleration, which is electrical interference from the engine. But not a buzzing from the speedometer.

 

[spock2001us]

It is not sound from the speakers. With the radio off, it still makes a buzzing sound coming from the speedometer cluster. It comes and goes and is louder depending on my speed.