Have got most of Bachmann releases and a few renumbered ones, All seem to suffer with one problem or another, basically the main problem seems to be the centre axle has no upwards play, on dismantling it this seems to be the main power transfer between the two outer axles have tried taking a minute amount off to aid play. Also a very good tip is to slightly loosen the bogie screw this frees up a little movement.
Also all NEM pockets are removed so they don't catch the front valance (still trying to get a wire loop to work)
Check the bogie steps don't catch chassis and AWS receiver doesn't catch the fuel tank.
As a good friend said to me unless your track is like glass their more trouble than the missus
I hope Vi trains next issue is a 66 cause these a pain in the derriere