I just gave 4 pans a good hard scrubbing with coarse stainless steel wool, then another round of fine steel wool - the spots came off with effort. Maybe give it a try.
I have not found steel wool to be helpful... at all.
I did muck up my Favorite Piqua 10 a bit.
Poured Crisco oil into the skillet when it was a bit too hot...
instant sticky glop in the center, that only got worse with use...
and because it is winter, I did a short term fix....
Sprayed the inside with DAWN POWER DISSOLVER, let sit for 20 minutes and then scrubbed with a Stainless Steel Scrubby and HOT water.
Not perfect, but much better, and put back in service.
When spring arrives I will re-strip in the lye bath, and re-season.
I have found that it is Very Important to heat the pan before applying any oil. It helps thin the oil out, therefore making wipe downs more effective.