Update:
After ignoring this problem for some time, I opened it up again for a closer look, and determined that there is substantial play in the shifter 'Yoke Bushings' (#30 in the picture).
I ordered up the repair kit (#18), along with new linkage bushings (#282 some play observed), and I'll let everyone know how it goes.
"Everyone", meaning the 5 readers or so who have this transmission, of course!
Link to picture of shifter mechanism
Note: If above link does not work (Growl!), paste the following URL in your address bar instead:
http://www.eccentrix.com/members/csnow/misc/shifter3.jpg