Help figuring out a reverser issue on 7750

[s0nic2]

Hello everyone. So over the past 5 days I've been meticulous servicing a friend's Sinn that has a Valjoux 7750 inside. When I first put the watch on the time grapher, it had an amplitude of below 190 with a really twitchy beat rate. Long story short (and I can elaborate if anyone wants) the watch is now back together running with an amplitude of 310 without the chrono and at about 305 with the chrono with virtually no beat error.

But, the one issue that I can't seem to solve is that with the rotor attached, it's very hard to wind if the rotor is held in place, and spins the rotor if I let it go during winding. First thought that came to mind was that it's a reverser issue with it possibly being gunked up or all together stuck. However, taking it back apart and looking at the reverser externally I don't see any issues. The gears spin freely relative to each other in one direction and lock like expected in another. Virtually no force needs to be applied to spin then. But when going back in, same issue. So what gives? If anyone has any suggestions or thoughts, I'd love to hear them.

Thanks all. 

PS, I haven't regulated the watch yet. 

[watchweasol]

Was the fault apparent at first or only since being rebuilt,  was the initial amplitude of under 190 before the dismantle. There is the possibility that a wrong screw in the wrong place is causing a distortion and therefore compromising the automatic assembly.  If the watch winds as normal without the automatic thats mre than likely.

I have attached the7750 sheets in case you do not have them.

1075_ValJoux 7750 Pages 8-13.pdf 1077_ValJoux 7750 Pages 19-23.pdf

[Nucejoe]

What haapens when you loosen the rotor screw a turn or two?  

[Plato]

Did you lubricate the reversing wheels correctly? Have a look at this video from 8:28 onwards:

 

[s0nic2]

Thanks for the feedback.  I will check the screw engagement later this evening and report back.  However, I will say that the screw that is being used for the rotor is the "short" one and when the rotor is spun it seems to spin freely.  Also, if the rotor is removed or loosened to the point where the gear teeth disengage from the teeth of the reverser, the winding becomes as smooth as expected.  It seems that the only element that causes the change in how the watch winds (i.e., smoothly vs hard) is the addition or removal of the rotor.

As far as lubrication, admittedly I did not use Lubeta.  Instead, I used 9010.  But it might be worth taking the wheel out and letting it go through the cleaning process again.  I have been using the L&R cleaning solution but also have a dedicated hairspring cleaning solution which is probably a bit stronger.  Is it worth dipping the wheel into that?  It's almost as if there is movement between the two reverser wheels, but not enough such that when the gears spin at higher speed due to manual winding there is not enough slip.