Knocking/Noisy dephaser?

[Ph1Rich]

Posting on behalf of a friend who is interested in buying a 172. The seller sent him the above video stating a possible knock on idle. Any ideas?

Cheers.

 

[DIDITNO]

I'd say dephaser, that's £650 to sort out

 

[MicKPM]

Its a fair bit cheaper these days. We do them for £550 and I believe AndyG is around the £490 mark.