How can I fix my 2 piece fiberglass fishing pole?

My 40 year old 2 piece fiberglass fishing pole will not cinch down properly when I put it together. The male end of the aluminum coupling slides very easily into the female end but will not cinch down. It is what they call an interference fit I think. The rest of the rod is great but if the 2 halves continue to flop around, it is useless. Please help!!