Durst L900 fine focus problem

Hey all, hoping for help with something which has been beating me for a few weeks. I have a L900 and the fine focus ( on the handle ) only moves the head up, but it slips and doesnt move the head down when I turn the handle the other way. Ive tried tightening the screws on the back, which makes it lock tighter but doesn't fix the problem. Here is a pic of the clutch plates? http://imgur.com/I3W1HUt
Is it a matter of replacing that white disk? Or roughing it up somehow? It seems to be made out of some fragile sort of stuff and im a bit cautious of making a mess of it. Normally I would have given up on it but I have the full set of masks, light boxes and matching lenses and would like to get this running. Im in australia if it helps.

I 'm not familiar with Durst so take this FWIW.

If the Durst has a counter balance spring adding tension to help in lifting the head, the clutch is probably worn and probably should be replaced. The question is whether the white part or the other face is worn.

As a SWAG the silver plate engages with the white one when making an adjustment?

As someone who can't resist "fixing" things like this, I'd try using some gasket material, cutting a disc the same size, slitting one side & slip it onto the shaft. That may increase the friction enough for it to work.

Gasket material is a thin cardboard material usually sold in auto parts stores in small sheets ~9X12". Failing that a hardware store may have a large enough fiber washer to work.
Gasket material would be thinner than a washer but either should work for you.
The washer would be easier to find they're normally found in plumbing area.. It's already a circle & all you would have to do is cut one edge.

Hmm, thats something I hadnt thought of, adding something the width of a car gasket might work. Yeh you have the basic model right its a big spring running up the back which returns the head to the top. I have been thinking about just adding more weight to it but the guy who sold it to me used it professionally for years and claims it works as is. He had no reason to lie since I picked it up for free..

Just thought I'd add a post script to this post, I added a sheet of thin all purpose car gasket and yeah. it kind of worked! it's useable now in any case , not perfect though. still a little sloppy but better than before.