Mag-tube Removal on Ithaca M37

[barnbwt]

Anybody know how the magazine tube attaches to the receiver? I can't budge it with any of the usual methods (that I'm not afraid will break it). Feeling around, it seems the tube is slid/screwed over a short section of tube that is inserted into the receiver. Mine is a '76 vintage, if that makes a difference.

Thanks for the help, ya'll,
TCB