AS1187

[fjseal]

I have an AS1187 movement that will not continue running when wound. It passes the wheel train 'blow' test both ways with no binding, and the pallet fork and escape wheel do what they should when moved with some power in the mainspring. However, when I set the movement down it ceases running; either after a few seconds or a good few minutes. The slightest touch has it running; it 'wants to go.' I have substituted another mainspring but that makes no difference. Should I investigate back from the balance, or is there something more obvious that I am missing? Any ideas would be welcome, thanks.

[watchweasol]

Hi  I should investigate the balance for cracked Jewels, bent/broken/worn pivots , The balance spring for concentricity and flatness also is the spring running in the regulator evenly (not laying on the posts).  At a last resort just fit the balance with no fork/pallet and give it a slight puff with the blower and check for freedom of movement.

[Nucejoe]

Remove the canon pinion to eliminate the minute train.

 Did you lube pallet jewels? 
Check side and end shakes on staff, fork arbour and escape wheel.  Check if escape wheel wobbles and possible misalignment of or damaged pallet and fork jewels. 

Make  sure the impulse pin is about or in beat. 
Supplement power manually to the barrel or a gear of main train. 
  Check its running in all positions.

Good luck.

 

[StuartBaker104]

Quote

On 4/14/2020 at 6:08 PM, Nucejoe said:

Make  sure the impulse pin is about or in beat.

...and talking of that impulse pin, is it securely fixed in the roller?

[Nucejoe]

Yes escapement is the prime suspect. Guard pin or the fork horn rubbing on roller can grind the running to a hault. I the check out with watchaeasol list. There is also a chance of guard pin or fork hoen rubbing on the roller. So many possibilities there.