Are you aware of any other significant differences besides the mainspring that come to mind just curious.
The project, it's not something I'm actively pursuing right now just in the research phase. I probably won't try to build the skx until I can disassemble and rebuild even if it is way simpler.
notice the flats. a large cresent wrench can turn this. you need a "fixture" to hold the case securley. i use the wooden block. this case has fine threads and might be "cross threaded". be careful, good luck. vin
I too agree with the others. A service, a new mainspring and regulating it would likely get your watch in perfect order. For a top notch modern movement like your ETA calibre 2801-2 the B.E. shouldn't be more than about 0.3 ms.
Thanks. I'm actually not the least bit worried about him for his future. He has a clear plan and knows what he wants and what it takes to get there. My middle son is another story. He's very immature for his age. Hoping he turns around some than later.