For warped ASM chips, don't even put them in the oven. Really. Just clamp them and leave them overnight. ASM chips are like Play-Doh compared to Paulsons. I found that if you use any heat at all on an ASM chips for even 15 minutes, the chips become squashed, and the chip faces suffer minor damage (flattening of cross hatching, etc.). I've had limited success flattening warped ASM chips by clamping overnight. The lightly warped chips and spinners tend to come out pretty good, but some of the really badly warped chips never get flat enough for me. Your mileage may vary.
One thing I'd like to do to make this process a little easier next time is to order some 40 mm diameter ceramic blanks. When you use standard 39 mm blanks, you have to be very careful to get the ceramics and clays aligned perfectly so that you apply pressure evenly over the entire face of the clay chips.
Good luck! I hope that helps. And as others have warned, be sure to test your process on old chips that you don't care too much about!