LGB Track Cleaning loco 20670 LGB makes a cool track cleaning loco. It can actually work well on removing the oxidation on brass track. Basically it has a loco portion with a motor, and then a front section that is pivoted, with another motor spinning 2 wheels that have an abrasive cleaning wheel for a wheel tread. There is a speed control knob on the top, rotate counterclockwise to make it faster. The newer units have a decoder in them, but I had very little success programming it, or finding out what CVs coule be set. The cleaning loco takes a pretty high voltage and about 2 amps, so don't try to use a wimpy power supply. Replacing the cleaning tires Over time, the tires will wear. They can not only wear down, but can get out of round, and then the unit jumps up and down and does a poor job of cleaning. The typical symptom is a "zebra strip" effect on the wheels, alternating stripes of clean and tarnished brass. Also, running it too long before attending to it will damage the plastic inner pieces, which are basically the "flange" to keep the wheels on the rails. First , you need to remove the gearbox cover on the underside to remove the cleaning wheel assembly. Before you do, you need to remove a small brace that is on top of the cover near the rest of the loco, remove the 2 screws, and the small brace comes off. These 2 screws also hold the back of the hood on. Here's the brace: Now remove the 3 screws that hold the gearbox . Note these 3 are shorter than the 2 in the brace. You can now remove the motor cover. Here is a picture of the cover: Now, the the wheel and axle assembly just pulls out. Here's what's left: Here's a used wheel assembly ready to be rebuilt: Each wheel is a "sandwich" of 3 pieces, an outer cover, the rubber cleaning ring, and the inner pice which acts as the wheel flange too. There is a small SS scres holding the assembly to the axle. In the picture above, you can see the wear of the rubber ring, and also wear to the "flange". Unscrew the old wheels, and be sure to clean out any string or gunk that has accumulated betwen the wheel and the bearing. Below is the set of parts to rebuild one wheel (the LGB repair package contains all the parts to rebuild BOTH wheels, including 2 new screws) When you reassemble, the blocks on the axle have slots that engage the chassis, and of course be sure to put it in so the gears mesh. Also, the brace only goes on one way, it's beveled to match the angle of the gearbox cover. Other issues Realize some of these units, especially the newer ones have a decoder in them, and the speed of the loco itself can be controlled by the decoder or the knob on top. As with any DCC loco running on DC, you have voltage losses through the decoder, thus this loco really needs 24 volts DC on the rails to run right, and it needs several amps. Another issue is that the weight inside can short on the circuit board, giving erratic operation, you can insulate the bottom side of the weight if this happens.