The big question here is: Did you glue the aluminum tube in as well?

If you didn't, you can saw the two halves apart up to and around the tube, and re-glue.

If you DID glue the tube in place, then you'll have to cut through the tube as well, but you can just try to find a tube that will fit inside. That may be difficult, but there are ways around it:

1. Get a broomstick and sand it down or bulk it up with paper and glue so it fits snug inside the tube and glue it in.

2. Find someone who has a lathe and turn a bar of aluminum (Or steel pipe) so it fits.

In either of these cases it would only have to be about 2" long