Howdy here it is as promised, hope its not too big.
http://i116.photobucket.com/albums/o...66bearings.jpg
What you need to do is make sure all the bearings are 'clicked' into place on the bogie, if the bearing sits between the wheel and the bogie than it doesnt allow free movement of the axle. Also when clicking them back in be careful of the gear, if the teeth dont fit properlly it will also restrict running.
Lastly when returning the bogie frame, do so from the coupling end, holdinng the bogie at the inner end slightly up with a screw driver so when clicking the frame back into its original place it fits in properly as can be quite frustrating the first few times.
Hope this helps and the picture aint to big. if it is sorry.
let me know if you solve the problem.