Phil;
Is there a possibility that the headstock lathe spindle is bent? A bowed
shaft would give those symptoms. It is possible to bow a lathe spindle by
over tightening a pulley set screw - if the pulley hole is irregular. I had
a lathe once with this problem (huge flat belt cast pulley with uneven
center hole). Check to see if the spindle is bent.
Jim

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James P. Riser
Http://www.JamesRiser.com