Seiko Sportsmatic behaving strangely

[Barnaby]

I have just finished servicing a Seiko Sportsmatic, calibre 410 (same as 6619).

Everything is fine when the watch is on the winder- consistently losing 30s a day, so should be easy to regulate within +/- 10spd. Before going ahead with the final regulation I wore the watch (I usually find that spd is different when worn compared to my winder). That's when the strange behaviour happened: the watch gains 3 minutes in a day. Fine overnight. The next day gains a lot during day (around 20s per hour). When I put it on the timer everything looks good- all 5 positions within +/- 30 spd, (and CR -70).

What could be causing this behaviour?

 

One possible clue: the amplitude is high for a Seiko - 310 degrees.

[clockboy]

The escape and H/S are the areas to inspect. For example, is there too much end shake with the balance. Is there a big positional variance such as when the crown is down or up. 

[Barnaby]

Escape and balance look OK. Positional variance isn't great but isn't terrible:

 

DU +30

DD +20

CD +20

CL -13

CU -11

CR -70

[Nucejoe]

Hi

Do you have a spare fork+ pallets to eliminate this one?

Are you video equipped to show escape to balance inclusive?  

Pin guard bent of pushed in? 

 

 

 

 

[Barnaby]

If there was a problem with any of these parts wouldn't the watch run badly when on the winder?

[Nucejoe]

38 minutes ago, Barnaby said:

If there was a problem with any of these parts wouldn't the watch run badly when on the winder?

310 degree and good time keeping, indicates higher wheel speed, the wheel can pick up even more speed (by strong sudden move of hand) such that impulse pin wouldn,t  be at the right position to receive energy from the fork horn, rather  passes by the horn ahead of time, so can happen if pin guard is bent.  No strong sudden move by the winder. 

Have you red  the thread titled "temperature dependence" ?

I hope this helps.