I'll try to find some black neoprene and replace the existing tubing. I've gone so far as to change the stock carb to the G23 carb trying to cure the problem but to no avail. The clunk is now about 1/4" from the back of the tank and falls freely from top to bottom. However, when pointed down, it will be out of the gas once the level drops to about 2/3rd of a tank. The last two times out, dead sticks were the last flight on my Big Boy. It's getting a little old, if you get my drift.[:@]