As far as I know there are no bearings. There are cast Iron bushings that the axle runs through. It sounds like your problem is the axle is rusted or stuck to the bushings and will not turn. The wheels turn on the axle when you go in reverse but the ratchets grab and turn the axle to run the beaters and floor chain when you go forwards. The axle goes through cast iron bushing blocks on the underside of the frame and then there is a sheet metal U shaped shield that goes under the floor between the bushing blocks around the axle shaft.
As far a how to get it unstuck, I would start checking for grease fittings on the cast bushing blocks, some never had them, and others have them or a grease cup, and grease it well. If you take off the beater drive chain and disconnect the apron drive and the axle is indeed stuck, then you could try driving it around forwards a bit more to see if that frees it up, if it does not then I guess it might be time to heat up the bushings and drive it some more. It is quite possible that putting a bit of a load in it would help it free up as then there would be more torque on the axle when you drive forward.
One more thing is are the wheels on yours the drop center spoked or the split ring?