That is exactly what I'm trying to find out - How to take it apart to replace the charcoal, because the original filter deteriorated and lost some of the charcoal.
I'm not certain that the bottom is sealed together or maybe the 2 holes are used to unscrew the base from the cansister. On the GM versions it was a simple r&r for the filters.

Does anyone have any experience breaking the bottom apart as Darren mentions?

The canister itself is in excellent condition so would like to repair and use the original if possible