R107, New Parts Kits and Manuals

I am trying to replace the mechanism that holds the rear of the hard top in place on my 83 380. I loosened the nut to remove the shaft but there is a plastic piece that fits over the locking mechanism that will not allow me to remove the shaft. Does anyone know how to take it off (and replace it when reassembling) without destroying it?

Any help would be appreciated.

Thanks