Let me add,
When you get yours, take it apart and thoroughly clean.
The track dust gets everywhere, and its essentially an abrasive.
Diassemble the cleanng axels, wheels, etc.
Never add weight to the floating cowl. The gearing is great if left alone. It is not if taxed.
The cleaning tires/wheels have a very long life. But the discs on which they mount tend to crack at the axel, a bit. Buy a spare set.
The cleaning wheel flanges shed nylon, delron, ???threads,
I pull on the flange edges to remove them before they spin off and wrap the axel. But, it will still happen. These threads add drag to the axel, and need to be pulled out regularly. I blow the dust out evertime i use it.
One can also reverse leads to the grinding wheel motor so that it pulls in the direction of travel. This helps on wet track on a grade. Otoh. Imho, doing so can increase the amount of dust under the floating cowl area. I have done both wirings. I think having the wheels pull in the direction of travel helps tracking through points and curves, a bit. It greatly helps on wet track, as i have had the loco stall, as the rough grinding wheels have equal opposing traction to the metal drive wheels!
Otoh, i think the normal wiring might reduce the amount of dust under the cowl, as its thrown forward.