A few weeks ago I repaired a used 24-105 for myself. I have purchased it in a box in thousand pieces for a bargain price. Everything was ok – excepting a strange noice from the stabilizer when switching on and off. Does it work – yes. Does it have any fault symptoms – not.
Excepting the fact, that the photos were blurred.
When I checked it thoroughly, I observed, that stabilizer was working only within a tiny moving field. The brake didn’t engaged the moving of the stabilizing lens element. Checking this is not too difficult, and IS A MUST AFTER ANY REPAIR. Watch through the lens and the camera to an object, and move the body (like small oscillations with the lens up and down, or left to right. Case the shutter is not pressed, the object will move in the field of view. Case the IS works (button halfway depressed), the image will not move in the viewfinder, better to say, only after making a bigger amplitude.
My one moved always, just after switching on the IS movement was a little bit less..
After disassembly of the lens: I have seen nothing. After disassembling of the IS unit, I had a feeling, that the small motor for the bake moves sticky.
And watching through my favourite 20x stereo microscope, i have seen, that the small white gear has been damaged. One teeth is deformed. And that was enough to stop the brake ring.
Fortunately I had an another bad unit in a box (electronic failure). So I changed the electronic/cable on them.
Is not too easy to get out the flex from this type of socket – I used some adhesive tape on the cables back, and I pulled then the tape, not the cable.
But be careful – the upper lens element has to be centrated after disassembly and assembly.
Just an another trick: the aperture flex cable always brakes in the same position.
At first, as I told in another post, cut the sharp edge of the last lens element to a round form.
Then put some textile-base adhesive tape on the flex cables back side.
Never forget to check on a repaired lens:
– the aperture on any zoom position
– the focusing on any zoom position
– the zooming
– the stabiliser switched off/on.