AIUI, there is some family resemblance between a 140 and an L5. If that is the case, please see if thread below is any help:
L5A vibration and clutch re-furb mini project
I have had a new vibration become apparant lately on the lathe. I think its only started since I finally put the levelling bolts in the corners of the cabinet, and set them for optimal coolant draining. Its something hitting a resonant frequency and can really be felt through any mounted...www.mig-welding.co.uk