problem with seiko 7s26

[ramrod]

i have a seiko 7s26 that i have used to make a rather nice pilot watch. i can't remember where the movement came from. it runs all day long while it is dial down. but, when i flip it over, such as would be worn on your wrist, it slows and stops almost immediately.

i have not taken this movement apart, but when i do, what should i look for?

[WileyDave]

guessing, but i'd say balance assembly or pallet/jewels incabloc, dirty, cracked, worn or bent pivot(s), too much endshake or not enough, seen this on pocket watches, takes a pretty hard knock to get Seikos out of whack, balance staffs and roller jewels are usually robust unless they are dirty. hope that helps

[rogart63]

Look for wear in the train wheel bridge and movement plate? Where the arbor is. That is a place where Seiko is usually worn. To much movement and the barrel will lock when you have the movement in different positions?

[ramrod]

well, i have narrowed it down by accident. i swapped the balance into an NH35 movement that i have also. the thing took off running immediately. it ran all night in the inverted position, but when i turned it over, it stopped.

so, it looks like the balance is dodgy. i'll pull it and look for a pivot to be damaged. this might be the solution.