as yet i havent tried to repair enamel damage.
  there was a coil i wound that had a wee bit missing.
  but as the wires it was laid up to were good i done nuthing.
  once the coils are potted only bad over heating will make the coils lose there insulation .
  as this is all a learning curve for me. its good i dont need worry about what i do with expensive new wire.
  and peter yes i found a motor that was the same as you talk about.
 it was a pain to try unwind. it to was pulling off the enamel.
  but as it was a fast spinning type thing. then that's why it had varnish on it i suppose .
 looks like transformers are better.  or the field coils on the stator .
  but the fact i found one thing pulling off the enamel. dident stop me in my tracks .
  my motto is .IF AT FIRST YOU DONT SUCCEED THEN TRY AND TRY AGAIN.
  i don't intend to build a wind gen with copper wire that's no good .
   far from it . i hope the wire i am using will be better than the cheap chinese  
  stuff that is being imported from Asia.
   nothing against  the chinese   as i do love there magnets.
   i think there trying to figure out what quality control means .
    yes sum wire is junk but that can be put in my scrap box.
    my wife has that nail varnish stuff .
  maybe i can bye her half a gallon for her birthday.
   who knows.
its a ill wind that dos no good