I took the binoculars and stopped down at the boat last night. The halyard and furling mechanism at the top of the foil looks fine, the setup on the spar is pretty clever, it would be very difficult for the halyard to wrap on the foil unless there was no tension at all due to the angle of the halyard.

On the other hand, things did not look so good at the drum end. I have added a photo for reference. There are four SS line guards that attach at the base and go up under the lip of the drum (the drum is anodized aluminum). In the photo you are looking at the drum from the side so you can see the location of the four line guards, they are perfectly aligned to block the furling line at the angle it comes off the forward most stanchion block. The furling line rubs on that starboard side line guard. There is also a strap that passes through the toggle and is attached with machine screws, however that is not a tight fit and allows the line guards to move around a bit. When the sail un-furls the line guards move counterclockwise about 1/2" and there is very little contact with the furling line. When you pull on the line to furl the sail, the line guards move clockwise and the furling line binds from friction. The "bang" was caused by me pulling on the furling line hard enough to pop the guilty line guard out from under the lip of the furling drum(and bend it out). That bent line guard was rubbing on the outside of the drum causing even more issues.

I replaced the furling line over the winter so it was still smooth and slippery the first couple of times out. It is now showing some wear and the texture is adding to the friction on the line guard. The perfect answer would be to rotate the guards about 45*, however I'm not sure I can do that. It was 88* and humid last night, I was in long pants after work and was losing troubleshooting momentum(and sweating like a pig) after a half hour or so. It appears that the line guards clamp on, although I'm not sure about the piece where the toggle strap attaches. This will require more attention then I had to give last night, it looks like a weekend project. If I can't loosen and mover those guards I have no idea how I'm going to solve this. The ideal angle for the furling line is straight in on the center line of the boat/furler. I have seen other boats mount a padeye in the center of the foredeck just aft of the stem fitting with a ball bearing block attached. I my case, that is the anchor locker hatch so there is no way to do that. It will have to be figured out before we leave the dock again.