Brand new sunny health treadmill belt surging under 4.5

I just purchased a sunny health treadmill from Amazon. I will link it below. Having an issue where under 4.5 mph the belt will “surge” I guess while you are on it like increase in speed for a split second off and on settling back. It does not change speed on the console. It gets worse as it gets to 4.5 then stops and works fine. I’ve tried tightening and loosening the belt with no difference it seems fine to me. Has anyone else had this issue with them or another treadmill? Not really sure what to check. I’ve contacted sunny health but haven’t gotten a response yet.


Sunny Health & Fitness Premium Treadmill with Auto Incline, Dedicated Speed Buttons, Double Deck Technology, Digital Performance Display, BMI Calculator & Pulse Sensors with Optional SunnyFit App https://a.co/d/09VfSIq