Vertex K8400 GT2 belt upgrade tensioner

After 6 months of good prints with the Vertex K8400 printer, I had problems with the quality of the prints. I tried readjusting, changing belts and I also upgraded to GT2 belts. At last I found that the problems were due to a worn out stepper motor. So an upgrade to GT2 belts was not really necessary. But now it is done, so I publish the GT2 belt fastener/adjuster that I created. You need to print 4 of this part and 4 mirrored parts.
I had to do some modifications to the printer to be able to