John,  I can't speak specifically about your Volksie's cables..... but think
you are on the right track in checking out the little gearbox and cruise
control functions for binding.  That was the case on two American vans we
owned.  Are you aware you can re-core speedo cables quite easily and
cheaply?  If the outer sheath is OK that's all you need.  It helps if you
have a small torch to silversolder the ends.....  you can buy the core
material at most autoparts places.  Fixed lots of Bug speedo cables that
way.

Glenn McComas, Queenstown, MD
87 Vanagon; 69 Baywindow; 87 v.d.p. XJ6; plus some cars that actually run.