This is how the focus mechanism look like

http://www.flickr.com/photos/18067251@N04/sets/72157626869741228/with/5791030324/

If your focus knob broke, perhaps you can try this method:

http://www.flickr.com/photos/photoplastic/sets/72157594558177497/with/403607988/

Some tips on possible quick-fix for the focus level stuck / jam problem

”

Reference:

http://www.apug.org/forums/forum51/78631-minolta-autocord-broken-focus-lever.html

If you want to loosen up the focus, you can:

1) Open the back. Maybe remove one of the door hinges to remove the back completley.
2) See that black cup around the lens? It simply presses in to place. Insert two fingers, spread apart, and twist. It should release after a few tries. Lift out.
3) See that large brass piece? On its outer side, it is threaded. It is this part that moves in and out as you focus, moving the lens panel with it.
4) Well, you can’t really see the threads, but if you can drip Naphtha at the joint between the body and the brass piece, do it. An eyedropper, syrige, or draftsman’ inking pen. Lightly, let it sit, a bit more, etc. Give it a few hours. The naphtha should be able to wick in and start loosening the grease.
5) Be patient, try not to flood it. Small applications over time will be safer for other mechanisms.
6) When (if?) it loosens up, exercise it. Then drip just a few drops of light oil into the same area from the back when the focus is set to infinity (brass block pulled back into the body). The basic idea is to dissolve the old grease in the fresh oil.

I did this with my first Autocord and it still works well, 6 months later. Since then I have completely disassembled the mechanism for cleaning on other Autocords.

Also, you’ll see two screws holding the focus scale in place, one on each side of the camera. Remove these, remove the focus scale, and you’ll have a much better hold on what remains of the focus lever. Might even be able to scab something on, superglue a block or such. With the scale out of the way, it’ll be clearer what the options are. You’ll also get a peek at the same focus mechanism and brass block. Another place to attack the old grease.

A third place to attack the old grease is from inside the viewing lens chamber. Remove the hood (4 small screws) and you’ll get another peek at the brass block.

Both of these places, be careful not to flood the camera with oil or solvent. Light, precise applications.

Great lenses, great design. I think only a Planar 2.8 will get me away from the Autocord and have me go back to a focus knob rather than the lever on the Autocord.”