[Heathkit] Type of Paint on Heathkit cabinets

[carl lowry]

I am redoing  4 SB-610 Monitor Scope Cabinets.
They all came from different sources within the country.
I am using Lacquer Thinner by a company named CROWN, found at local hardware stores.
Want to take cabinet paint down to bare aluminum metal, then sand before zinc chromate  and repainting.
Been soaking the cabinets in a quart of Thinner at a time.
Paint on two of the cabinets came right off - lifted up - after 45 minutes of soaking.
Other two which seemed to have a more greenish ting soaked and soaked and no paint came off.
Just the yellow-brown stain from previous smokers and ages of dirt.
Did Heathkit use two different types of paint on their cabinets ?
If so suggestions for removing - the other - type of paint.
Thanks for your courtesy of replying.
73s Carl, k4zrd