Vintage SEIKO 7005-8022, ca. 1974

Taken before the service...
The movement was not that dirty, but running erratically. It turned out that the balance's hair spring had been "violated" and also the main spring needed to be cleaned.
The Thai year 2530 corresponds to 1987 (simply subtract 543) and at the bottom not fully in the picture was a mark 7-79. Thus I am confident that 1974 represents indeed the manufacturing date of this watch.