Can you identify the issue by sound

[Enso13]

Dear Watchmakers,

I am a beginner watchmaker and will be servicing an Omega 1020 very soon. Would you be so kind to help me identify the issue using this sound file?

https://soundcloud.com/yura-k/omega-1020-metallic-sound

As you can hear the metallic knock is present between the balance swings - tick - ding - tock. Have any of you had any experience with a similar sounding gremlin? What could it be?

Thank you for listening.

[Melt]

Found this.....http://forums.watchuseek.com/f6/clinking-hairspring-868632.html

Or its the impulse jewel coming round and hitting the the pallet (but I think thats more of a bang sound).

So maybe hairspring hasn't been centred or has moved on staff?

[praezis]

 Your extra noise is a "ringing" hairspring. Happens quite often but is usually harmless. Probably comes from a sticky blade that  comes  off from one regulator pin delayed and hits the opposite pin. This noise can be as high as the escapement noise and disturb a timing machine. 

 Btw. Mr. Ranfft's assumption in the above link is not true.

Frank

[Enso13]

Thank you Frank, that sounds relieving. Did you have an experience of eliminating this sticky blade hit? I suppose if it is sticky, a good clean and lubrication should do the trick...

[Enso13]

5 hours ago, Melt said:

Found this.....http://forums.watchuseek.com/f6/clinking-hairspring-868632.html

Or its the impulse jewel coming round and hitting the the pallet (but I think thats more of a bang sound).

So maybe hairspring hasn't been centred or has moved on staff?

Thank you for your input, Melt.

[praezis]

Cleaning balance and cock may help. Often this noise disappears already with a changed position of the watch. 

Frank