CD,
I also have a National Two Spool machine. I have found that there are some "emergency mending Kits" sold at Wal Mart -- the spools contained in those kits WILL fit the National Two-Spool canister. Too bad you are missing the canister -- I think I saw one on E-Bay a while back with a minimum starting bid of $350.00. Sure am glad mine has the canister!
Jeanette