Response from Jonathan: Dennis,

When you say width adjustment knob, we are assuming that you mean the potentiometer (or pot) that controls the width on the monitor chassis. Keep in mind that your horizontal width coil may need to be adjusted/replaced as well. See our post on Adjusting The Horizontal Width Coil for more information on that particular part. You should be able to order a replacement pot or coil from many of the companies listed under the Arcade Parts Suppliers & Distributors heading on our resources page.

While a width pot or coil going out could cause this issue, it’s usually the power supply section of the monitor that causes problems like this. We highly recommend checking our post on Troubleshooting Games That Are Playing Blind for some great tips on how to solve this issue. Unfortunately we are not familiar with your particular monitor but you can always try locating a manual and/or schematic for it which should also help you out with the troubleshooting process.

Hope that helps. Thank you for your question and good luck with your repair.