Dave Liquorice submitted this idea :
Some had a mechanical means that wound up a kicked the motor in the
opposite direction if it started backwards.

A small hairspring within the drive linkage which allowed it to wind
itself up and some sort of pawl to stop it if it tried to go the wrong
way. If on switch on it tried to go the wrong way it would wind the
hairspring up to the point where it would have enough force to spin
itself in the correct direction.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk