On my 4500 industrial tractor, I'm having issues with the clutch throw out bearing. I can start the tractor, put one shifter in gear, and when I got to put the other shifter in gear, it just grinds. I can start it when both shifters are in gear, then drive it. I assume it is the throw out bearing needing lubed. I hear about a cap for the grease to go in, but I can't seem to find it. Does anyone have pictures of this lubricating cap, so I know what to look for? Thanks for any help.