I had this happen to me awhile ago.The first time it happened I hand wound it onto another reel & some bobbins.

The next time I had bought a tube of G-S Hypo cement ( has a fine applicator for detailed work )for something else but I still had the pieces so I glued all the pieces back together.The reel is still like new & it was a lot easier to use than superglue.The G-S Hypo glue was bought on the internet for $3 or $4 including postage instead of about $12 in the shops