Landice L7 - Speed issue

I have been trying to diagnose my treadmill problem.

I was running on it a couple of days ago and the speed did not seem accurate. I had it set for 9.0 mph and it felt like I was running at about 6. When I stepped off, the track speed increased. It seems to be fairly accurate at walking speeds, but not when running.

I had a friend run a voltmeter across the capacitor when I was on it and it showed seemingly normal progression of voltage when I increased speed without load. Then I tried running on it at a higher speed (and it seemed slow), the voltage tested at about 90V. As soon as I stepped off, it shot up to over 100.

I have looked at the brushes and they seem to be in good shape. The speed sensor appears to be properly adjusted.

Thanks for your time.