mine did that when the small stainless piece (opposite side form latch) that sticks on where the hook rests, fell off. I replaced it and never had a problem again. Make sure that small piece is still attached. I'm not home or I would take a picture of the area I'm talking about. If you look at this picture: http://cgi.ebay.com/ebaymotors/Harle...#ht_500wt_1065

they are the pieces in the middle towards the outsides that have a semi triangular shape and 2 holes in them.

 

Also check the lock tab.
I had one do this on my old Road glide.Had to loosen the lock tab nut and move the lock tab a little so it would clear the bracket.

While your in there,good idea to check the latch screws and the latch nuts.

 

great thread...luv this place

 

Also consider the seal around the lid getting old and squished causing the lid to loosen up. I noticed the difference when I installed new stretched bags and had to install new lid seals... WHOA tight lid!

Call me crazy though, but I always lock my lids regardless ever since hit a rough bump and flipped a lid open on the freeway at about 80 mph.

 

Here's your parts manual. Its a sticky under General HD Chat.

http://partsfinder.onlinemicrofiche....m_oem/hdmc.asp