Y-belt attach AnetA8

The original part seemed a bit loose, and I eventually got round to investigating. My belt measures 1.7 mm over the teeth, 1.2 mm in the teeth. Although the short section in the original looks OK, the long section is 0.5mm too wide.

The remix ix the 4mm version, with the 2nd path made narrower where the two belts overlap. The other end is slightly tighter, but relaxed a little so it doesn't push the belt sideways.

I have also split off one of the mountings to act as a retainer, and provid