If you ran the threading feed right up to the up to the micrometer stop expecting it to disengage the feed drive it is quite likely that you have broken the shear pin provided to protect the drive gears.
There are no overload clutches in the 1024 VSL drive train. The shear pin is it. When threading to a stop you are expected to drop the half-nuts before hitting the stop.
Check that the drop gear train between headstock and gearbox is rotating. If not its the shear pin.
I think it lives under the the top gear of the drop grear train. The one taking the drive from headstock to banjo gears.
If I read my poorly scanned parts book copies correctly that gear is on a top hat shaped bush with a drilling through the rim for the shear pin. If this is correct the shear pin engages fits into a matching hole in a flange. Book pictures don't give a very good indication of how its all set up.
Clive