Pete if this is the style you have then there should be a plug at the other end of the spool valve (opposite where the shift rod hooks on)
If you remove the plug and the shift rod you can see if you can move the spool back and forth.
That way to you'll see if it is just the spool stuck, or if the linkage is bent and binding also.
Also once you get the rod disconnected and the cap off you'll be able to remove the spool valve so you can check the O-rings. Just push it out backwards (t words the plug you removed)
And if all else fails wait till I can get there