3400 Tach Low Reading

[ctpres]

Overnight my L3400HST (with only 220 hours) tach does not show right RPM. Max. reading around 500 RPM. Any "been there done that" ideas on where to start?

 

[wushaw]

Check to see if it is still connected and cable is greased....if it is a cable??? I know my B7500 was and my Mitsubishi is.

 

[JOHNINMA]

I just had to replace my tachometer drive on my B5200 (internal gears in the drive stripped out). Your problem sounds like how mine acted just before it stopped working all together.
If the cable is ok as mentioned by another poster check the drive assembly that spins the cable.