Coenter

Hello, After years of useful info in this forum i end up making an account because i need help: my Ultimaker 2 is making a scratch sound, after hours of investigation i found that it is the X-axis in the hot-end-carriage that is ''scratching'' the linear bearing when moving backward? is that possible? when i look at the slider-block it is moving up and down with the past of the axis it is sliding on. I noticed the axis on the front side is also moving but just the tiniest bit. Video of the slider block and the scratching sound: all belts are on tension and i tighten all pulley. Any idea?