Phil, have you recently tightened the rawlbolts and inadvertently warped
& twisted the lathe bed? Does the wobble disappear after you true a
sacrificial block attached to a faceplate? Do you put too long a tenon
or dovetail on the blank for the chuck to center & hold? Does a M900
have a rotating headstock? Diagnosis is usually difficult---treatment
often easy. Arch

Fortiter,