Cheers to CARSON356. Found the control valve(?) to the left side of the radiator, tapped it a few times with a light hammer, suddenly there was a loud shrill noise from somewhere nearer the rear bulkhead and up she came. :)
Now there is a faint clunking sound in reverse, so I've only moved it 30 feet out into the fresh air and abandoned it again. Don't want to blow another $6k gearbox. :(