Pei Der Han· Banned
It is most likely that the difference between the 6r15A/B is changes to the date wheel and manual winding mechanism which were problematic early on. A part # check could verify this.7s26b said:The 7S26B movement also incorporates a new barrel/mainspring assembly (part # 0201 075), a different setting lever/yoke spring (part# 0388 177)-same as 6R15 , and as mentioned above a new balance wheel (part# 0311 050)-same as 6R15. I am not sure of the differences between 6R15A and B movements. Information taken from 7S26A Seiko tech pdf and NH26 NE15 TMI tech pdf.