what company makes non-thinning brush-on sealers? the only sealer I have is MM's sealer marked for airbrush only. However, they write this on alot of their products and I disregard it. When I paint this stuff onto a model (I usually use it for figures) it, very slowly, starts taking paint off. After a few brush strokes the base color can be seen. This MAY be because I give the paint 1-2 hours to dry, but I'm not sure. Do I really have to resort to my slightly unorthodox airbrush setup, or is there a brush-on safe alternative to an oil and acrylic sealer?

I believe the "sealer" you are using is the "sealer" for their metalizer line. If it is, it is for airbrushing, and if I recall, (been a few years since I did a NMF aircraft) it is a lacquer based sealer and will take off your paint for sure.
If your are brush painting, try Polly S Flat. It's acrylic, and brushes excellently and leaves a nice flat finish. It also comes in gloss.

Hey Lance, you can also use Future floor polish. I't also acrylic. Easy to use, just paint on light coats and it lays down flat w/ no brush strokes. You can also mix w/ any flat base acrylic to achive from a dull to shinny coats.

you're reffering to spectre lance? if so, great game