Mowing Plastic shroud over pto knuckle

[Dgoatrider]

M tring to replace the shear pin on the brush hog knuckle. There is a plastic cover over the whole shaft. It flares over the knuckle I removed a small black cover over what looks like a lock ring. I don't want to take it off unless I have to it is a eurocardan cover on a FC cutter. I can't get the knuckle with cover there and can't see a way in. Help I want to get back to cutting today