after many trials, we still have problems with fibre slippage on left end but right end works perfectly.
For various winds the fibre aligns excentrical on the DH roller during the linear pass to left end. An additional tool before the roller to keep the fibre in the centre only showed minor improvements in the winding process. Furthermore, it seems that the elliptical moves are slightly different in terms of speeds and rotations of DH and the fibre tension drops significantly more on left end than right end.
With different improvements, left end looked different than right end but process could be run automatically until all passes of one group are complete. After the mandrel shift which follows the end of one group, fibre always slips of at left end because distance to polar opening gets too large.
Has anyone faced similar problems? Any help is welcome!