After Some layers, it looks like the calibration is lost.. (1 reply)

Hello All

I'm new here, and this is myn first question hope someone can help :-)

I have à prusa mendel i2 which was printing okay , but after setting the belts à little tighter. I get the following problem.
The half of the gearwheel layers is printing okay [attachment 18428 image.jpg] and then hè lost his precision.
I have checkend the z spindels ...

Richard