Zero plate won't ground to cutter.

[Stagecraft]

Years of flawless performance and this issue just popped up...Older PRT Alpha equipped with a 5HP Colombo spindle. When setting the zero with the plate the cutter is not grounding, as in no ground light on the control panel. If I touch the plate anywhere else on the gantry or the side or case of the spindle the ground light comes on just as it should. The only place I can't ground is to the cutter or collet. FWIW this machine was never equipped with the alligator clip setup the way our other Shopbot was. Any suggestions as to what could be causing this?

[Gary Campbell]

Inside the spindle there is a contact bushing from the case to the armature. You wore yours out. Time to invest in a clip.

Test this by touching the plate to the spindle body and then to the bare armature shaft. This will also eliminate a bad connection thru the bit, collet and nut.

[Stagecraft]

[QUOTE=Gary Campbell;195739]Inside the spindle there is a contact bushing from the case to the armature. You wore yours out. Time to invest in a clip.

Thank-you Obi-Wan!