Original Grey Technic motor from 1977: 6216a

[Jens Bauer]

I always thought that the "m" suffix was a quick n dirty ad-hoc filename submittal, with "m" for "motor"...
I think we should renumber that to the usual ...a, ...b, ...c, ... scheme.

If it's "renumbered", then remember that there are at least 4 variants of the motor.

The very first variant of this was made in 1977, the position of the rubber-band groove is near the end of the axle (870).
The second variant has the oilite bearing and on the top (between the studs) it has an arrow pointing forward (maybe 960, maybe only released in a plastic bag). I think this one was released in late 1977 or in 1978.
It seems the third variant, is the 12V motor, which is black (880).

The fourth variant is likely the "expert builder" variant with an extra prong hole and the rubber-band groove closer to the body of the motor (eg. Chris Dee's files). This was the variant that came with a new battery enclosure.

I do not know if there are more than one 3-prong hole variant.
I haven't seen a 12V variant with 3 prong holes and re-positioned rubber-band groove, but it might exist.
Note: The 'service pack 1175' (4.5V motor in a plastic bag) could contain any of the 3 grey variants, including the 1982 variant with the middle-prong hole.