Thx for quick replies.
My first thought was that the furling line was getting fouled (I had wrapped up way too much the first time). Stripped out a bunch - but maybe I need to keep more tension on the line as I reel out the sail. Given the drum spins easily by hand I think this is the most likely culprit.
Line is running clear to a block on the bow pulpit - so that shouldn't be the issue.
Boat is on salt water, definitely no servicing in last few yrs. Just bought some marine lube - I'll see if that helps.
I'll be sure to sort it out rather than just going with more force! Given the small line I couldn't see how it would have been designed to withstand winching.