Tom, the key is that the old laminate must still be tightly bonded (tap around with a hard object to check for voids. As Jack says, sand with 80 grit. The other trick is to use a solvent based adhesive in this application rather than a water based one (take care to provide sufficient ventilation, turn off appliances and gas, and where a respirator). For an excellent book on the subject of laminate countertops, including this approach, pickup a copy of Making Plastic-Laminate Countertops (title may not not be exact, but it's close) by Herrick Kimball. You can order it from Taunton Press (www.taunton.com). Go to BOOKS and do a search; it'll pop up.