I finally ponied up some moolah to upgrade my Haloscan account so now all the old comments are back. Hurray!
Up until now, Haloscan had been dumping comments into a black hole after three months. The only annoying thing is that the comment number under each archived blog post still shows zero. So you don’t know if or how many comments are on any post and just have to click to find out. I’m not sure if this can be fixed, but I will check on it.