My boat had the pin/stuffing box replaced already when I purchased her and has not had an issue since. I have rebuilt the CB winch and replaced the cable and adjusted the control arm. I would suspect that you would either have to remove, or at least loosen the control arm to be able to get at the packing material. The control arm should have a set screw/bolt at the bottom that holds it tight on the pivot pin. loosening that set screw should at least allow you to move the control arm enough to get in there. I would definitely go ahead and replace the packing material since the port is already open and you have access. It'll be far easier to do it now that than to have to open it back up again later.
I don't know if that was any help, but I'd be happy to answer any other question that come up.
hunter Legend 37 Semper Paratus
Formerly - Tartan 34C Yawl