Shaker Rattle noise..

[Mustang Pete]

Having an issue with the recently fitted shaker motor.. dont sound right, too much of a woody knocking sound, rather than a rumble.
Have screwed down tighter, and tried again. Isolated motor and that seems fine, but getting a knocking sound as if its hitting the cabinet

Can only think of mounting it on some small spacers?? Has anyone else had this issue?

 

[Mustang Pete]

Think i may have found the issue...the bottom of the motor housing is warped..a washer should sort it...i hope?