I recently installed a GE dishwasher MODEL # GDWT668VOOSS. The countertop is not wood so the only supports are 2 screw holes provided near the top of each of the two side mounting brackets. . The dishwasher needs additional support. What do you recommend to use for lower supports into the adjacent cabinets? Should I drill holes into the side brackets (same as the two holes provided by the manufacturer along the side brackets or is there a kit or other suggestions.

I found a solution without altering the dishwasher. Cut a 1” wide piece of board that is approximately 1/2 inch thick. Cut length about 1” longer than distance from back legs to wall. Cut a v notch so when you butt it against the leg it will not slip off. Swing it around so it wedges between the wall and the back leg of the dishwasher. You might have to trim some off length during this process. I got my length finally right and tapped it in place with a hammer so it fit snugly between the wall and the rear left leg threads. Didn’t need to use the other one for the right leg because one side wedged did the job.