Timex also had a 21 jewel selfwindig movement in a few of their watches: The caliber M74 is basically a M72 with hour, minute and second indication with an additional selfwinding mechanism.
It is also the only Timex movement, I’ve ever seen, which is marked with the jewel count.
Technically, as all other Timex selfwinding movements, the rotor tends to loosen and rattle. It does not affect the winding efficiency due to the heavy weight, but it makes the whole watch rattling while being worn. On that very M74, the mainspring is broken, too.
|Number of jewels:||21|
Nickel anular balance|
|Balance bearing / direction hairspring:||Bridge|
|Adjust mechanism:||Hairspring key|