Hawk DLX Exhaust Gasket?

[Do©Hawk]

Hey everybody. I took my Hawk DLX out to play in the snow in my yard today. Had a great time, but when I started the bike, I noticed quite a bit of exhaust gasses leaking from flanged joint in the exhaust pipe where the tri-clamp is.

Is there supposed to be a gasket in there? I've had some issues with the clamp since getting the Hawk last August. At one point the clamp fell off entirely while out on a ride. Fortunately it turned up by my kids' bus stop. I bought a lock nut for it to replace the thumb screw. It has stayed pretty secure since, but like I mentioned above, there is quite a bit of exhaust leaking at that junction.

I haven't noticed any performance issues, but I'd still like to stop the leak. Any suggestions?