heisler driver wont turn

[ALBYRNO]

The geared axle in rear truck of stearns heisler turns stiffly with gearbox/driver assembly in frame.With gearbox removed driver turns freely in frame.Gearbox with axle assembly turns freely outside of frame.When gearbox is installed in frame driver turns very stiffly.Any ideas?Does the new heisler truck come with gearbox I can't tell by picture.

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The replacement trucks for the Heisler do come with a gearbox.  I would test the trucks with the side rods removed, and see if that helps.  One or more wheel sets could be out of quarter.

Reg Barron