Sounds to me like the spindle is bound, not the plate. I'd lay it flat, spool side up (you'll have to support the reel to make room for the handle), then a couple light drops of penetrating oil around the spindle. Leave it along for a few days. May have to repeat several times over a couple weeks.
Also, not just the spindle screw that is reverse threaded, but the plate too. To remove the spool, wind backwards.
I was always the kid that tried to muscle things. Patience has come with age and a pile of broken "forced" things.
Once you get it open, clean it really well, using a pipe cleaner and light oil though the spool opening and on the spindle.