I unscrewed the driver cover and I'm in the process of shimming 3 of the 4 axles as you guys suggested to correct the sideplay (the driving axle is much tighter because of the gears)
Also the traction tires are coming off--there's no grooves underneath and the tire drivers look identical in diameter to the rest except their surfaces are smooth not scored.
There was a ridiculous amount of sideplay. How did Rivarossi expect this model to run correctly? I'm using fiber washers with notches cut out so I can push them onto the axles--I don't want to tackle popping drivers. Hopefully I won't have to correct the slop in the siderods too.
Thanks again for everyone's aid and encouragement. I always hated rubber tires--they belong on cars not locomotives!