Hi Scotsman: Welcome to the forum from a transplanted Scotsman. Although a different chassis, (Ford front gasser) , I had a similar problem with my column mounted shift lever not wanting to come out of park. I removed all the shrouds around the column and sprayed all the moving bits I could find with a silicone spray, then went underneath and sprayed everything on the linkage with a grease spray, so far no re-occurences of the trouble. I realize your will be a much different setup, but lube may help. Lang may your lum reek.
04 Triple E Commander, 07 Ford Expedition