Hi OP,
Have you tried the CW forum for advice ref the SH21 movement? CW are in a very small minority on here but I for one will vouch for them. I only have one watch of theirs but am mightily impressed with the quality, can’t speak for longevity as I’ve not had it for a year but don’t expect any issues, although mine (Super Compressor) has a base SW200 movement.
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