Some seams look towards the end like the welding spots got longer

Possible causes:

  1. Welding pressure:
    Is the welding pressure mechanically always guaranteed?
  2. Upper roller:
    Is the upper roller touching the Z-bar?
  3. Lower welding roller:
    Is the lower welding roller too low?
    Welding center must be in the center of Z-bar!
  4. WEC-O3 circuit board:
    Change the existing with a new one.

     Make sure all jumpers and all little blue pontentiometers are in the same position!