"Foot-related Resonance" is a Ralph Buscarello term. I believe what really happens is frame distortion which distorts the bearing alignment, and in the case of motors, distorts the air gap which creates an electrically induced vibration as well. But there also may be a pure resonance present as well.

Hello all,
I am a first time poster here and just want to say that this board is full of great info and has already helped me out immensely.

I have seen a similar problem to the one discussed here. After the motor was sent out for repair due to a bent shaft, we found a high 1x vibe at the motor ode. The ode bearing was then checked and changed in place...but the high 1x remained. The motor was then pulled again for complete inspection (i suspected the bent shaft was still there, or there was bearing looseness)...we found the DE housing was about 0.005" over bored. After the housing was resleeved and reinstalled there were no more issues.

A bent shaft or poor bearing to housing fit makes sense to me.

Nate