Hi Jim ,
I guess you have one of the later versions of the lathe ,
that has a relay connect a 27 ohm breaking resistor across the motor when the mains is disconnected.
( something I've only seen on Real Bull lathes not Sieg )
the old Machinemart CL300M (Sieg C2 ) lathe I have just coasts to a stop
while its a pain the belt failed , It would of been a bigger job if the plastic double gear on the spindle broke
( can happen if the parting tool digs in and jams the spindle)
despite Ketan's advice , I have fitted the 3 part metal replacement from ARC
its made more difficult because the original keyway in the spindle is too short
the original key only can drive one gear and the spacer
at the same time , I fitted taper roller bearings to the spindle and brass gibbs to the top slides
make it a lot easier to part off (no longer something to avoid)
John