Charcoal contamination

[Dead Parrot]

If pellets that size are getting past your air filter to the carb top, the fail is with the air filter. Also, the charcoal canister usually vents into the same hose as the PCV valve which enters the manifold below the carb.

Good chance a close inspection will find gnaw marks on the flapper valve hose and probably a hole chewed in the air filter. Might double check around both exhaust manifolds for rodent nests.