Just an update,
I rebuilt the pot with a little hot melt glue replacing the tiny plastic lug & it now functions as it should, according to the multimeter. However, as someone previously forecast, the shorting out that was part of the original problem when the pot fell apart inside, has damaged the PCB or one of the components on the control board. When I re-connected the pot & wiring the lathe works but only at one speed the equivalent of about half the max rpm, regardless of where the pot is rotated to.
Looks like I'm gonna have to bite the bullet and buy a new pot and control board from the dealers! I assume it would be cost prohibitive to have it tested and repaired professionally, unless anyone else knows better?
I will wait till the new pot comes from China first though, just in case the problem is in the old repaired pot.
Cheers, Griff.