Response from Jonathan: Dave,

For monitor problems such as this, we recommend starting off your repair by trying to adjust the monitor first to see if it solves the issue. Check out our post on Adjusting An Arcade Monitor for more information. In this post, we discuss raster monitor which usually have horizontal/vertical size and position adjustments. Vector monitors (such as the one used in Tempest) usually have an X/Y size and centering which work similarly to their raster monitor equivalents. Try adjusting these values to see if it helps your problem.

If the problem continue after trying to adjust the monitor then you could have an issue with the monitor chassis itself. At this point, we recommend checking out this Color Vector Monitor FAQ and Guide which has some great information on how to troubleshoot issues with monitors such as the one in your Tempest cabinet. Of course, please feel free to contact us again if you have any additional question about your problem.

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