The problem has now been solved:
There were two reasons:
- the propshaft touched the tunnel and
- the universal joint touched the end of a screw with which an eyelet for our dog was fastened.
The solution:
The tunnel was set approx. 1.5 cm higher and the screw was replaced by another one (instead of the hexagonal screw a door hinge screw[has a flat head] and inserted from bottom to top instead of from top to bottom as before.
