Buying a broken lens. Canon EF-S 17-85mm f/4-5.6 IS USM

I recently found a great deal on a Canon EF-S 17-85 on Craigslist. The only problem was that the zoom was stuck.  I contacted the owner and inquired if the focus and IS were working.  The owner confirmed that everything functioned except the zoom.  I mad arrangements to meet at a local Starbucks. The sekker was really friendly and I ended up talking way too much and not looking at the lens properly.  I noticed while it was attached to my camera that something was funny with the focus but i got a confirmation on my first try so i just accepted it and didn't even look at the focus window. Oops!

I now owned a lens lens that had a stuck zoom and no response from the focus motor.  I paid too much.  If I have to buy a zoom barrel and a focus motor to fix this I will be paying the same as I would for a working lens.
The bright side is that this lens appears otherwise to be in excellent shape. The optics are clear and have no blemishes and the body is perfect.  There is a little internal dust but that will be taken care of when I have it apart.

The dis assembly begins with the removal of the rubber zoom ring,  under the ring there is a rectangular plastic cover you need to peel this off.

 Underneath this cover is the zoom brush. This brush is very delicate and needs to be removed carefully.

Beside the zoom brush you see a brass bushing with a black screw inside it.  There are 3 off these and they will come out later.






Using a 00 size Philips screwdriver remove the 2 small screws holding the contact strip to the mounting ring.
Then a 0 size to remove the 4 screws holding the mounting ring to the lens body.  The center plastic spacer needs to come free before you can release the ring from the contact strip.  I lift the mounting ring carefully and slip a finger underneath and push the plastic ring out.

 Once I removed the mounting ring i noticed that the focus motor ribbon was disconnected (circle).  This is confirmation that the lens was probably dropped.  As there is no damage to the outside of the lens I an hopeful that it will be an easy fix. The ribbon with the arrow is for the switches on the outside of the lens barrel and needs to be removed before pulling the barrel off.

There are 6 ribbons that need to be removed  to take off the circuit board. Starting at 12 o'clock and going clockwise.  The first has two locking tabs at the edges.  pull these back with a fine tip flat screwdriver and carefully pull our the ribbon. The next two have brown gates that hinge up.  place a small flat blade under the gate and lift.  the gates hinge up and the ribbons come loose.  The next 3 are simple pull our ribbons.  They all have tabs on the side to pull/push on.  the one at 6 o'clock is already removed.  There is 1 screw holding the pc board onto the lens body.

 Once the circuit board is removed there are 6 screws holding the focus motor assembly in.  Don't try to take the focus assembly apart. If it's faulty you can order a complete unit to replace it.  I unfortunatly do not have a photo of these 6 screws.  Once you lift off the focus motor assembly (last picture top right) you remove the 3 screws with the brass bushings we looked at earlier. and remove the outer zoom barrel.

The screw in the white circle is the culprit in the jammed zoom ring.  They tend to work themselves loose. Especially in a lens that has been dropped.

In My case the screw had come completly out and was lodged down beside the front element.  the slider that it connects to in the inner zoom barrel had slipped and was stuck as well.  I had to continue well passed this point to get the lens repaired.

 At this point I was totally focused on the lens and didn't take any other photos.  I ended up with a really good lens that takes really nice photos. Once reassembled the zoom work perfectly, nice and smooth.  The focus works flawlessly ass well. (Lucky)  It is much better than my 18-55.  My 28-135 lens that I have from my old elan 7 film camera still produces better contrast.  The wider angle on the crop sensor makes it worth the effort.