Mantichore began quarterly publication in the early 2000s when Blackmore rejoined the EOD apa. In 2009 when Blackmore became OE of SSWFT apa, Mantichore was also distributed through SSWFT and is still currently going quarterly through both apas.
Many of the earlier issues can be found archived on www.scribd.com. (Blackmore intends to upload all issues but is catching up).
Some hardcopy issues up to the time of Brooks' death can be found housed in Cuyler W. 'Ned' Brooks' fanzine archive at: http://www.fanac.org/Fannish_Reference_Works/NedBrooks/z102.html