Had the same problem.
I found that the wheel/switch itself was not actually the problem. Other parts of the linkage were sticking, and not allowing the springs to return it to idle state.
I went wild and dissassembled every ball joint for a 'clean and lube', then cleaned and lubed every other moving part on the linkage. I also cleaned and lubed the little wheel, which was not rolling. I used lithium grease throughout.
What a difference! When I first got the car, I thought the accelerator was designed for big Germans with strong legs, then I realized it was simply all gunked up.
1986 300E 5-Speed 240k mi.