Tach trouble.(pics)

[BamaDave]

I finally got the factory tach put in my truck and at idle it is reading 1750 rpm. Surely this can't be right. I did put the filter in the wire from the tach hook up on the HEI to the "tach" hook up on the gauge. I guess the thing is going to have to be rebuilt or refurbished. Can anyone recomend a place to get this done? I hooked the 12v terminal on the tach to a ignition source of +12v. I think this is right. When I rev the motor it goes way outside the tach readings. I would appreciate any help here.