EF24-105 f/4L Buzzing and shaking

Well my three year old (i.e. out of warranty) 24-105 f/4L has decided to start to pack up.

When I attempt to focus the lens often buzzes and the viewfinder shakes, looks like an IS issue so I switched of the IS and it still does it. After a while of trying to shoot with it my camera body (40D) error codes 1 complaining about connection to the lens.

Have cleaned contacts on both lens and camera body, my other lenses don't have issues but then none have IS.

I have a second camera body I will try when I can get it out of storage, in the mean time anyone else seen this issue?

OK so more detail on this, it is not the IS but something to do with the aperture diaphragm. Anything other than f/4 crashes the camera with Err-01. Aperture preview also is only works before the first shot is taken since the camera was powered up, after that it does nothing regardless of aperture setting.

does it do anything differently at either end of the zoom range? might just be a ribboncable has let go...

joeseph wrote in post #11832874
does it do anything differently at either end of the zoom range? might just be a ribboncable has let go...

It is better at 24mm than any other position.