I recently purchased a vintage Pfleuger Hawkeye fly reel that is frozen solid, I got the clicker to work by soaking in wd4o but cannot get the spool to turn. the crank is really too delicate to exert any real pressure, I am spraying the inside of the spool bells with wd40 but that does not seem to do the trick. A friend said to soak it in gasoline for a couple of days but I am not certain if that will damage the rubber (or Bakelite, not certain) side plates. Any info would be helpful. How about an ultrasound machine? But I don't know what type of solvent to use...

Try soaking in Salt away .. that stuff does a lot . And not overly harsh . I think salt gone are the same chemicals as salt away.

https://www.youtube.com/watch?v=Ejih-SP4IkA Hope it helps