if you have a ZF box probably a broken bulk ring allowing the sleeve to move too far forward ..though you say gearlever moves ok with engine off...have you checked the linkage ??seems odd that the gearlever moves ok with engine off but sounds like it didn't move with engine running ..disconnect linkage at box and see if you can manually put veh in to neutral with a set of molegrips on the shaft
norb, May 2012