Refitting a loose impulse jewel in fusee movement

[Bill241]

I picked up this rather nice silver pair case pocket watch- a little unusual as it was made in 1912 and so relatively ‘modern’ but has a very traditional construction. I suspect it was made for the Scottish market by Rotherhams of Coventry. 
 

It hadn’t been cleaned in years and was barely ticking. I stripped it down and overhauled the movement. My usual approach is to clean the balance pivots cleaned with soft pith wood then placed the balance in a small sealed jar of IPA for a short cycle in the ultrasonic cleaner. 
 

I had always believed the impulse jewel in these old English lever watches was friction fit (as with the pallet jewels), but apparently not in this example.  The shellac has dissolved and the jewel dislodged itself after reassembly but fortunately I recovered it- the little beauty was sitting in plain sight on top of the barrel bridge! 
 

I’ve obtained some shellac flakes, and managed to refit the jewel. I applied heat via a short length of brass wire mounted in a small pin vice to melt the shellac- a bit messy (it was my first attempt) as quite a bit was left on the roller table. I placed some foil under the roller to make sure no shellac found its way on to the hairspring. 
 

The watch ran for several hours overnight but has stopped. I suspect the impulse jewel was not quite secure and during the course of the 100,000 or so impulses overnight, came loose and is now at an angle. 
 

I will have a second attempt after taking out the jewel and cleaning off the excess shellac but would appreciate any pointers to get it right. 
 

Is it necessary to remove the roller and apply the shellac from the other side? I preferred to avoid that if possible, lest I irretrievably loosen it in the process.  I used Mark’s technique of creating a thin strand of shellac and applying the strand and heat but I don’t think I’m getting enough shellac around the jewel to guarantee it is secure. 
 

Many thanks! 

Edited January 8, 2023 by Bill241
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