Craftsman 900.370510 emits rhythmic noise

This is an electric mower. It runs but emits a rhythmic noise. There's a link at the bottom to an imgur file with a .MOV video.

It was given to me recently; I just tried it yesterday and got this noise. I bought an electric back in the 1970s and used it for 40some years. Trashed it when I ran it into a tree root and (I think) bent the motor shaft.

Any help with this much appreciated.

Harmonic ringing on an electric mower is normally caused by either a blade which is unbalanced or a motor going bad. I would remove the blade and run the mower. Noise gone blade bent or unbalanced. Noise still there, motor going bad.

Sounds worse with the blade off. Not good news.

Got to be the bearings I reckon; I'm tempted to tear it down far enough to look.




thanks for the help