I'm betting the problem is in the linkage. You can take the two short rods off the lever assemblies on the transmission. Then see if you can move the levers. You should feel the detents as you move the levers when they slide in and out of gear. Both levers will have to be in the out of gear position for the transmission to be truely out of gear. Use the line drawing I sent you as a reference. The area you should be looking at is on the lower right of the page.
