I've upgraded to MT 3.x and comments are now available and working for all entries!
Sometime last fall an unrelated upgrade caused Movable Type to start giving errors when posting comments and trackbacks. The source of the error was the YAML library used by MT-Blacklist, so while disabling it would fix the problem it would also allow a torrent of spam to reach my blog, which was simply not an acceptable solution.
Until now I have not made it a priority to fix this due to the low level of comments my blog gets anyway, but now I finally found the time to upgrade to the newest version of Movable Type and it's superior spam blocking functionality, thus getting rid of MT-Blacklist and once again beeing able to recive comments and trackbacks on all entries. Enjoy!