Hello. I have little bit modified china laser with ketai gold board. I use my machine everyday and its works fine.

Now I have small problem. If I make cutting works like circle, starting point and ending point wont contact. There very small difference. Yesterday I tighten my laserhead belt littlebit . Today I saw this problem. Difference is very very small. Any help? I clean mirrors and lens Also check aligment. They are fine. If I make jewelry so almost everytime it cuts fine but I see starting / ending point on my cutting works..