I phoned Marlin this morning and spoke with Mitchell who spoke with their transmission guy; best call I have made in a month! For the record, he had me remove the detent spring plug on the driver side to loosen things up, on the theory that it stuck or rusted as long as I have had it stored. I sprayed in a little liquid wrench in and gently bounced the shifter in the direction it needed to go. Bingo! I now have reverse and 5th! Thanks Marlin Crawler!