Tudor 7928 with wonky 2813

[tribefan 6,768]

 

This is a $80 gate watch with a raffles dial that NCRich lumed and installed, along with some bezel fading, maybe even a new crystal. All in I've got a little over $200 into this and can fit it out with oyster, rivet and Nero strap options. Love this watch, problem is  that the movement randomly stops during wear and at rest. Like this from the factory. It will run for 10, 20, 30, 40 minutes fine, then randomly stop, stop start, and it's been pretty consistently doing this. There is nothing obstructing the balance wheel that is visible. I've witnessed it stopping, but usually I look down four hours later that the time is 10-15 minutes behind.

So I set it up on the timegrapher and it was wildly out of adjustment. I played around with it for a while in multiple positions and finally dialed it in to this:

I put it back together and was wearing the watch while researching what that pattern means, the random beat dots on one side, and I could hear the rotor spinning.  So I was moving my wrist around to spin the rotor and when it stopped, the second hand stopped. So I took off the rotor, and now it's running like a champ, lost 5 seconds in 16 hours of wear and rest.

Back to the dots, that picture is taken with the crystal face down, when I flip it 180 degrees those dots shift wildly all over the place, amplitude drops as low as 200, but it stays in time pretty well, it will only move a few seconds. From what I've read that is indicative of a hairspring issue, which means no fixey by me, swap the movement.

If I don't have to remove stems and hands, I won't, plus there is no guarantee the next 2813 will be any less wonky then this one. Is there any harm to running this without a rotor? I do not care if the auto doesn't work, I get plenty of reserve winding it. Any other ideas that don't involve stripping or replacing this?

 

[NCRich 13,798]

No it hurts nothing to run it as a handwind.  I use 2813s to replace handwinds in watches all the time.

This is just me, but the hairspring is probably dirty.  I would first take a puffer and blow air at the hairspring several times to try to dislodge whatever might be in there.  If that doesn't work I'd take the hairspring assembly out and dip it in lighter fluid, swish it about, then extend the spring a couple times , then put it back in.

If that doesn't work I'd pull a hairspring out of a broken 2813 and put it in there.