It needs to be loose when you furl and unfurl -- I'm sure there are instructions somewhere about exactly how loose.
Steve Pettengill, who was for years Hunter's official boat breaker, was showing me a boat with in-mast furling for an article I was doing for CW.
He got on the boat, looked around, and uttered something unprintable. The boat's "operator" had broken, IIRC, the turning block for the boom vang. Steve said is was from grinding on the outhaul without first releasing the vang.
All these parts have an effect on each other.