The photo above shows the 3.0 mm nut-driver and the extra M 2x4 hexagon head screws or bolts that are included with the K-28. The nut-driver include with this K-28 was extremely sloppy. Although LGB/Aster supply extra bolts with this loco, take care not to round the heads of your bolts.
The picture above shows a size comparison between a dime and one of the tiny assembly bolts. Great care should be taking when handling these bolts.