A tension disc assembly (25mm discs,spring, nut) from a Singer 29K fits.
A Pfaff tension assembly doesn't quite work - discs fit and nut threaded on ok..but the spring is too long plus wrongly configured (Pfaff has an extra disc split slotted to fit onto the split post rather than the spring nib ended to lock onto the post)
Auckland Sewing does carry some Singer 29K parts ...but no tension assembly showing on his Trademe store... just ask.