The laquer thinner may be your problem.
I found this on a auto painting forum.
"Your problem is the lacquer thinner you are using! Lacquer thinner will leave a film on the surface.
You NEVER EVER use lacquer thinner to clean with"
I would recommend going to Home Depot and getting a pint of Acetone. I used it on my roof and it will not harm it. Just know it's very flamable like most solvents.
I believe this is what the directions recommend.
Acetone is what labs use to clean thier glassware (at least years ago). It leaves no residue.