RAT

Yes, individuals can contact any US Seiko dealer just to get parts, however it is up to the dealer as to if they want to sell the parts, and unless they have a watchmaker in house I doubt they will. Myself, I sell only to other local watchmakers when they are in a fix and cant get them any where else or need technical help.

Your information is incorrect. I am not an authorized Seiko service center, I am a authorized Seiko dealer and Seiko USA does indeed sell parts direct to its dealers. The point however is that a quick login to Seiko's website shows that the genuine Seiko crystal, 310P03HN02 is not obsolete, and in fact Seiko USA has over 50 in stock.

No they do not sell to individuals, however I am an authorized Citizen USA dealer so with a simple phone call I have access to parts and technical information.

The Seiko part number for the movement is U7N3620 it is far from obsolete in that Seiko lists 50+ in stock. Also Miyota is a Citizen brand, it will not fit in a Seiko.

I called Citizen in California, and they do have part 087-105 in stock. However 085A has no part of that number. Now If you are talking about the Minute wheel and Pinion for a 0850A, it is part 072-1050 If you are talking about the Intermediate for second wheel it is part 087-1020 and Citizen has both in stock. Here is a list of all parts https://boley.de/en/caliber/watchmovements/citizen/2047

I called Citizen in California, and they do have part 087-105 in stock.

310P03HB0A is the correct part number, also 310P03HN02 is NOT obsolete, Seiko USA has both in stock.