A.S. 1970/92 All workds then escape wheel not turning. Why?

[LMS]

I have an AS 1970/92 that was fully wound. I needed to drill out a broken screw in the barrel arbor and straighten the hairspring, other than that all seemed intact. I cleaned it, polished the pivots, lubricated and assembled. I got reasonable amplitude (260-270 and fairly decent on the timer in 5 positions).

Then it stopped working. The escape wheel stopped advancing. Moving it from the movement holder to the timegrapher seems like it's dislodging something (pallet fork?). If I take out the balance and pallet and replace it; it works again (done this 3 times). However, the same fault then develops moving the watch about. I cannot seem to find an issue with the pallet fork. Pivots seem OK and it's definitely properly seated top and bottom. 

I am very much a learner and I'm not sure what's going on. Power from the mainspring through the train looks reasonable (wheels turn and some backspin), but like I say my experience level is about zero and a very tiny bit.

I've attached some photo's and video (youtube links- playlist for the videos below). List of content:

1_Train Test.mp4
2_HSpring.png
3_Bent HS Pin.png
4_Straight HS Pin.png
5_Working.mp4
7_Pallet Fork OK.mp4

7a_pallet fork pins.jpeg
8_Pallet Not Working.mp4
9_Escape Not Working.mp4

All help will be very, very gratefully received.

 

 

 

Edited January 25 by LMS

[nevenbekriev]

1. Wait for the movement to stop.

2. Carefully remove the balance and pallet fork. Be sure to prevent the train from getting free and spin.

3. Carefully inspect the train wheels. The escape wheel for sure will have free play, it is seen on the video. May be 4th wheel will have slight free play too. The first wheel that has no free play is the one that is stuck. The reason is between it's pinion and the table of previous wheel it is meshed with. May be bent tooth on the table.

[GPrideaux]

The escape wheel flopping about as shown in your video 9 indicates that no power is getting to the escape wheel. That cannot be caused by the balance or pallet so don't be distracted by them. You need to look upstream from there at the train of wheels, following the advice above from @nevenbekriev.

[LMS]

Thanks for the input. I followed the tips and found that the issue was between the barrel and the centre wheel. I checked all the teeth, everything was in good shape. The end shake was good, but I believe the issue was down to the side shake which was sloppy allowing the teeth to disengage.

I closed both holes top and bottom to tighten up. I would like to report back success buy (being honest) I am afraid we had another terminal failure that was unrelated and purely down to my stupidity.

I feel that I've learned a lot from this experience, and I cannot thank you again enough for taking the time to give me some tips. It's appreciated.