How to repair Kohler master shower volume control trim
 

I've had a Kohler master shower for about 10 years or so, and the volume control trim knobs have come off. This is a link to a picture of the knob, http://www.plumbersurplus.com/Prod/Kohler-K-T9472-7-CP-MasterShower-Volume-Control-Trim-with-Cylinder-Handle-Polished-Chrome/45182/Cat/1196

Inside there is a little screw that seems like it should attach to the stem coming from the wall. However, the head of the little screw is covered by the big cap on the end of the knob with the little indentation (you can see it in the picture).

Any ideas on how to get this knob back on?

http://www.homecenter.com/uploads/documents/13645.pdf
It appears that the cap is just push in.

It does push on, but then it won't stay on. Inside the cap is a little screw that has something to do with it staying on I'm sure. I can push it on and use it to turn the water on and off, but then it pulls right off.

http://www.us.kohler.com/general/warranty.jsp#faucets

It has a life time warrenty. Give them a phone call and get there suggestions . This sit has there numbers.

This parts diagram should help...

http://www.kohlerserviceparts.kohler.com/ServicePartsPage.aspx?DocumentID=b6a34e34d56944a2b 010ceb81dff3292&ModelID=4585a0cddd7949ce8a80e8a169 c87c67

Thanks for the suggestions. I'm still trying to get it figured out. I've looked at the diagram I found for what I think is my actual knob, http://www.us.kohler.com/onlinecatalog/pdf/1097384_5.pdf but I'm still not much farther along. The screw in my diagram is actually attached to the handle, can't tell how to get it out.

Redwood, thanks for your link, but that diagram looks like it goes to a control with a handle sticking out, where as mine looks more like the one in the link I put here.