Ok I finally figured it out myself after hours of prodding and fiddling.
- First had to disassemble the entire motor to get
the crown off the machine after removing the
armature and mounting screws.
- Broke the plastic clutch ( drive pinion) with a
screwdriver
- used a crescent spanner to hook on the locking
plate of the motor arm and banged away until
the locking plate slowly gave up its grip.
Turns out the previous owners probably never cleaned the underside of the motor arm in the last 30 years, and then left the machine idle for a long while. The kitchen grease had waxed and bound up so hard that even 4 cans of WD40 were wasted. Anyway managed to get the whole thing apart with only the loss of the plastic clutch and the already broken drive arm release toggle.
Rumi, February 2014