Ron,
IIRC there are some charcoal granules refills out there that you could use to replace what's in there now 40+ years old. You'll need to google for it, & then be careful in opening & resealing the canister to not damage it.
The NOS canister will be hard to find, but it should be the same part for 73 & 74, & maybe on the 72s too.
Good Luck!
Tom
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