The small follower pin that rides on the AFC Fuel pin is sticking and doesn't seem to want to stay free. I've cleaned it, lubed it, cycled it over and over, but after leaving it for a few minutes, it seems to get "sticky" again. I pulled the upper half off of the pump, but can figure out how to get to the seal to replace it. I have the Bosch DGK 121 gasket kit that should have the correct seal or o-ring, but can somebody tell me how to go about replacing it?