Belts constantly skipping

My x,y, belts are constantly skipping messing up cuts. I have tightened the belt as tight as I dare and they still skip. How do I fix this please. The machine - Masuter 3S is useless as it is.

I just got mins last week. I made two carves that came out okay. But now having issues w it locking out so i get it.
As for your question. The only thing that comes to mind is, did you install the belts correctly? The belts have to go under the tab and through the hole on the bottom. Then under the clamp. I made that mistake then noticed the belts were not recessed all the way dowm. Also the teeth face down.

Hope it helps.

Check to make sure all the allen screws are snug and the tension is decent. If you have 9mm belts, that is a plus. Also check for debris (chips) and vacuum regularly.