Alyce,
Looks like your missing a nut. It should go on the threaded shaft with the brass nut up against the carbon pile. The little brass piece goes on that shaft too.
Here is ArcaicArcane's blog about repairing a controller: {
http://www.archaicarcane.com/what-a-pile-of/ }. Hope it helps. If not tomorrow I can take one of mine apart and take a pic or two of it.
Joe