I sanded down the crazed spots and proceeded to paint the lower section of the Air Serpent. I used both the 'new' Krylon and Testor's enamel. Both were compatible with the primer and each other. To fix a failed attempt to draw a pattern on the body with a Sharpie, it appears the primer also covers Krylon and Sharpie ink without crazing. I'm wondering if the previously-bitched-about incompatibility is related to thicker areas of Fill'n'Finish. Anyway, I think I'll still try another primer next time.