I also been having problems with Testors when spraying.
I can only spray for about 10-15 seconds and the paint will coat my needletip and clogs. I have to swab the tip with laquer thinner to clean and it clogs up again. I changed thinners, Isopropl ( sp? ) alchol, water, tamiya thinner, windshield washer fluid all do the same thing. So I've stopped using Testors. Tried and true Tamiya always works.
Grendels, do you burnish the edges of the tape before you spray?