If those don't work, you can give this a try: http://www.cotronics.com/vo/cotr/ca_putties.htm
but it's $35 a tube.
However, it may be cheaper (read easier) to buy a new firebox. I'm told that the one from http://www.kamadoking.s5.com/whats_new.html
will fit these eggs. I know it defeats the point of trying to do a refurb, but these are replaceable parts. At some point you have to cut bait.
Then again I've been too cheap to order a daisy wheel top, so feel free to sprinkle a few grains of salt on this post.