You might consider using Trondak U40 Perma-Gloss instead of epoxy. It is a one part urethane rod finish that goes on very thin, it has a consistency just a little thicker than water.

Most graphite ferrules are designed with a slight taper on the connecting parts, this means that the deeper the ferrule goes into the socket the tighter the fit. If this is the case with your rod something might be preventing the male end from seating correctly. You might try rubbing some chalk or colored grease pencil on the male end and see if you can figure out where it is binding. I have needed to fine tune the ferrule fit on some of the rods I built. You can do a lot of tuning with some very fine wet/dry sand paper, I used 1000 grit and 2000 grit papers followed by crocus cloth to polish. I found the finer grits at an auto body paint supplier.

I agree with Smernsky's comment, what you describe sounds a lot more like a cracked ferrule, or an out of round ferrule. Make sure you check this out completely before putting a heavy load on the rod. Casting with a cracked ferrule might do a lot of damage. If the ferrule doesn't seat well (ie. full contact on all surfaces) you can easily split the blank! Hair line cracks can be very hard to see.

If it is a crack it can be fixed with an over wrap of thread or a very thin layer of fiberglass cloth, then over wrapped with thread. I was able to find some very thin extra light fiberglass cloth at a hobby shop that sold model airplane supplies, the material was used for glassing airplane wings. They aslo had graphite cloth, but it was too stiff for this type of application.

Nylon or polyester thread has a lot of stretch, it may not be the best material for a repair, I have used kevlar thread or GPS thread for repairs successfully, I then over wrap with rod building thread to hide the ugly colors.