I uncovered in my selection of old stock I got from an auction an automatic Seiko chronograph 6139. I read a little about some problems these watches had, namely the clutch on the centre chronograph wheel and the seconds hand mounting.
I am not sure if my diagnosis is close: while the chronograph is running the watch keeps time pretty well (within a couple of seconds per day worn on hand). Not always, but more often then not, when the chronograph is stopped the watch slowly stops (say it takes 3-4 seconds). When the chronograph is released the watch starts running. The fly back button does the job properly, start/stop/restart button works well. The watch had issues with the hammer click (was too strong - not original hammer spring) but for the time being it is ok.
I did not disassemble the watch yet as I am waiting for the original hammer spring. So this is a little hypothetical/frivolous question: Is there a chance that the (weak spot) centre chronograph wheel needs just cleaning and oil rather then complete replacement? Parts for this movement are scarce and the centre chronograph wheel is unreasonably pricey and the wheel itself - as far as I found out is not serviceable. Any comment will be appreciated.
Picture for movement ID.
Barrel and center wheel are different across A, B and C versions, details on my sheet: https://docs.google.com/spreadsheets/d/e/2PACX-1vRN2UULQKTfKmhRStZhDdIOIQrqd6sPB-g6x2SKyQQjOvTBjG_7TQXQhAT4f1WqAX5QAPkIimi-3jqd/pubhtml
I think only the C version is interchangeable with the NH3x. I am ready to send one to Giuseppe, but if he wants to buy from Cousins I suggest that for 15 pounds more he gets a complete new mov't, and use the current one for practice, resell or even build a custom watch.