Were they I wonder already both under the SSIH umbrella perhaps? Not sure. My point was that maybe an Omega bumper spring might work!
My 6546-1 says hello Cal. Tissot 28.5-21. Tissot produced many calibers for Omega prior to the merger. This caliber was supplied by Tissot to Omega. According to theses indications, I can tell you that the Tissot watch with movement number 1838649 and reference number 6546-1 was produced on February 17th 1948 and has a calibre number 28.5-21.
I had no idea Tissot used bumper automatic like that, it really is almost identical to the Omegas of the time which makes sense, probably very robust as well
Tissot even made beefy lugs, clover crown seamaster look-alikes... Another 28.5: (bad phone Pic, I don't have my nikon at hand)
My watchmaker was able to bring this mess of a movement back to life so yours is definitely salvageable.