But what the heck.
I don't think I'd previously mentioned this on the old forum, but in the last week of November, forum member Mithra, a.k.a. UK eBay seller exwharf, had listed three NOS 7Axx stainless pushers as '7A28 / 7A38', but without stating any Seiko part number for them, or which models they were suitable for.
https://www.ebay.co.uk/itm/Seiko-7a28-7 ... 3859876721
7a28 7a38 and others steel pushers with springs, new unused
The part number 81400669 shown on the ziplock packet was indeed for the circlips. So your guess as to which models these pushers are used on is as good as mine. Or possibly not.