As above the tracta joint has probably moved I used Vaseline to stiffen it up. I also found that the "face" of the bevel gear box had gone elliptical due to the beating it had taken over the years. So that the wheel station cup wouldn't seat fully home and the cork was showing as in your case. I took the end of the wheelstation and checked it would slide in easy first. I had to dress the damage out with a die grinder and flap wheel.
Once the cup fitted into the bevel gear box I reassembled the wheelstation,greased up the tracta joint and it slid together a charm.