when I run on my treadmill, it has suddenly started feeling like it briefly stops the belt whenever I land my stride. I’ve tried greasing the board underneath the belt with silicone grease according to the manual, but that didn’t help. Any advice on how to fix this? Could it be the belt that needs tightening?

[SOLUTION] It was just belt tension, it had become too slack. A quick tightening fixed the issue completely.