Replacing the capacitors on the top side of the logic board can help, but I think the symptom you've described and checkerboard pattern best indicate issues with the RAM. One thing you can try is to remove the sticks of RAM from their slots and thoroughly clean the contacts. You can use Isopropyl or denatured alcohol as a solvent on both the cards and slot contacts. Also, try a pencil eraser as well on the contacts. For more stubborn caked on filth, use a small wire brush specially built for circuit boards. Radio Shack sells a cleaning tool kit with the brush; catalog number 64-087, sells for $12.99. Not sure if there is a ROM SIMM slot on the Classic II. Can that be verified? If so, clean that as well.

73s de Phreakout. :rambo: