When place on dirty windows, the WINBOT X does not follow its normal cleaning pattern, moves slowly, erratically or stops. What is causing this?

On very dirty windows the accumulated dirt may increase the friction between WINBOT X and the glass, which can cause WINBOT X to move irregularly. 2 or more cleaning cycles can be used for dirty windows. Remember, WINBOT X is designed for routine maintenance rather than fist-time or heavy-duty cleaning. Be sure to wipe WINBOT X’s cupule, driving treads and squeegee before each use.