What is the procedure to disassemble the charcoal canister to replace the foam element?

Did not see it in the factory manual, if anyone has the pages showing details please post. This is for a 1972 model though believe they are all the same

I don't think it comes apart. All you can do is replace the fiberglass filter at the bottom.

I believe the filter just tucks under that crossbar on the bottom.

Larry

Yes, the filter just tucks in the bottom but the OP wants to take the whole thing apart and replace the charcole inside. I don't think it comes apart like that.

I had and extra one and tried to figure out how to take it apart. It was glued together and ended up in quite a few pieces.

Does the grille twist off?

It's listed in the "Lubrication and Maintenance" section of my '77 van FSM, but the later cannister appears to be a different design:

I think the bottom of the early style canisters unscrewed originally. It looks like they were glued in though. Not to mension the years of heat cycles has warped the plastic somewhat.