For some future helpless sap to find via Google.

I just spent an hour trying to unwind a the seat belt off an inertia
reel on my 1982 diesel Westfalia which I had removed to lubricate and
wash the seat belt.  The reel will NOT unwind unless it is oriented the
same way it is mounted in the van!  That makes sense... keeps the
(belted) occupant strapped in while the Vanagon is upside down.

BTW, after washing the seat belts in my (front load) washing machine and
giving the inertia reel mechanisms a very light squirt of (non WD-40)
lubricant they work like a charm.

Bret in St. George, Utah