Hi G-town. I had a similar problem with my 744 and it turned out to be lack of lubrication on the gear selector rods, in my case the solution was either take the gear lever off and dowse the rods and selector plungers with oil or, if your 44 has a pulley, run the tractor for several minutes with the pulley in gear. I ran SAE 90 gear oil in the gearbox as it splashes more easily when cold. I hope this helps..
Jack.