Here is a better picture, without the grease (previous picture was taken with my cell phone; I was at the side of the road).
http://lymanhall.smugmug.com/Trucks/1953-Chevrolet-3100-Truck/i-fc4rDLw/0/L/Box1-L.jpg From the position of the levers, you can see the transmission is in 1st gear, but the pawl has slipped down to the 2-3 fork, making it impossible to shift out of 1st. Numerous re-adjstments of the arms at the shift box have failed to cure the problem, which is why I believe the problem lies with the box itself.
