Davis sail track stops, or...
Davis Marine makes three different sizes of sail stop. One will fit your mast track. Each one has a knurled wheel which makes it very easy to tighten in place or release. They work well, are very inexpensive and most sailing stores stock them.I use two on my mast, one above the gate (the opening where you feed the sail slugs into the track) and the other below the gate. The upper one holds the main up when the sail is down and the lower one keeps the lower two slugs in the track when the sail is reefed. They are both tied to the mast with a short length of dental floss to keep them from falling overboard. I also keep a third one below as a spare.It sounds like you don't trailer your boat much, so another option is to make up two strips of aluminum about an inch wide. The strips should be about three inches longer than the gate, with holes drilled at the top and bottom so they can be screwed to the mast. They should be attached (after the sail is fed into the track) so that the inside edge of each strip lines up with the edge of the sail track. To remove the sail, remove the lower screws and swing the strips out of the way.This method is nice because when the main is lowered the slugs come all the way down, allowing the sail to stow more neatly on the boom. You also won't have to mess with two sail stops when it's time to reef. Good luck.PeterH23 "Raven"