Clean Lubricate Adjust.
Movements from this era were a hold-over of the pocket watch era where movements were made to standard sizes (for these little wrist watches they were ladies pocket watches) then fitted to cases (you were able to mix & match a bit). To an educated eye, the design on the bridge and layout of the movement should give an idea of who made it and then what would work as a transplant.
I Had a similar watch from around the same time period that had a 7 jewel movement (which ran beautifully when I got it- then I dropped it). With the assistance of
@Canuck - I was able to source a running replacement movement from a pocket watch that was actually a much higher quality. I took both the wrist watch and pocket watch (I got from eBay) to my watchmaker and it was a drop in replacement (after he did a CLA).
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