As good preventive maintenance, pull off the two covers over the main swing gear on the bottom of the crane pedestal. We are working on a friend's truck that got water down into the gear cavity, rusting it badly. the rust and resulting crud got between the gears, first caused jerky motion then locked up and would not turn. The water also took out the Timken bearings on the idler gear and the gear driven by the swing cylinders, finally blowing the swing cylinder activated gear up out of the housing, bending the rod of one swing cylinder and the cylinder's anchor eye on the hoist frame. Thanks to good luck, the gears can be saved. This whole gear mechanism should be kept full of lube and the integrity of the felt seal at the top inner edge of the large gear covers kept intact to prevent water getting down into it. This seal and one at the bottom of the cover on the side of the idler gear housing are not the best, so attention to them is required if the truck sits outside where rain and snow can put water past the seals. Bearing failure is guaranteed if this happens and is not corrected quickly.
Nice truck, it should serve you well.