The freeze spray method is a crock of sh*t.. im not sure who started the rumour that it is a good way to remove Mylar but it is responsible for more ruined playfields than any other method... once again - you are gambling that the mylar has less grip than the paint to primer below it. When removing Mylar gambling is a mugs game.

..Not knocking you Oldskool, but i wish you had posted here first and i would have shouted loudly to steer clear of attempting this... we could have saved quite a lot of paint

Unfortunately got this off the PINREPAIR website and I believe the freeze works better on newer games, not these old girls.
It is all good though as I love a challenge and am learning heaps and I really like the feedback. 
" Give a man a fish and he eats for a day - teach a man to fish and he eats for a lifetime"