VFit Los Angeles 2 Treadmill runs then slows and back to speed again?

Hi, noticed a few other requests for help with this type of treadmill, so thought I'd give it a try too.

Treadmill runs but over the last week or two it has started to slow and then speed up, not in terms of speed selected, it will never go over the speed of the programme, but now and again, and now more often than not it slows for about a second every say ten seconds and then back to speed. I have had the cover of and run the motor without the drive belt which was tight and it seems tio run fine with no load, but when drive belt back on and adjusted, it starts again. Running belt is running true.

Any ideas?

? motor
? terminal

Many thanks in advance, Rich