Long story short, I damaged a spool shaft and ordered a new spool. Can I transfer the 15lb floro I have on my damaged spool onto my new spool? Bad idea? good idea?

You can just tie the line to the new spool and reel it right on from the old spool. Your new line will have lots of memory due to being wrapped tightly and being on the small diameter but give it a soaking in kvd and troll it next time you're out to get any twists out of it.

You can just tie the line to the new spool and reel it right on from the old spool. Your new line will have lots of memory due to being wrapped tightly and being on the small diameter but give it a soaking in kvd and troll it next time you're out to get any twists out of it.

 

^nailed it

i've transferred line numerous times from a reel to a reel. works just fine.

I do this when the braid on my spool feels like a rag and basically fish with the other end

Braid is different than mono or f/c.  In the past I've soaked the line in warm water then spooled it up, but always troll the line out before fishing.