This sounds like a sticking or defective key on your controller keypad. The Video Manual, Chapter 8, Testing, Run Machine Diagnostics, Check Control Panel explains how to test your keypad for stuck or defective buttons.
test keypad.jpg
The process is as follows:
Check control panel
Push all of the buttons on the control panel one-at-a-time and verify that the corresponding image turns yellow on the
computer screen.
Turn the "speed/shuttle" dial on the control panel and verify that the "speed dial rotations" changes accordingly on the
computer screen. The number should count up to about 1.0 when the dial is rotated once clockwise, and back down to
about 0.0 as it is rotated once counterclockwise.
Click the "LED test" button on the computer screen. All the indicator lights (except the power light) should illuminate
one-at-a-time on the control panel, synchronized with the illumination of the corresponding images on the computer
screen. You can also click the individual images on the computer screen to manually turn the indicator lights on or off in
different combinations to further check their function.
If the lights seem dim, check for a problem with the supply voltage and do the hold test.
Otherwise, if any of the indicators fail to respond as described, the controller is faulty and should be replaced. If the
problem is limited to the control panel buttons and the panel seems physically worn or faulty, you can try replacing just
the control panel first.
You can purchase a replacement keypad directly from Plasmacam.
control panel.jpg