Ad5x and Mileage Wheel

New multifilament printer owner. I've occasionally been getting error e0109 which is "mileage wheel not spinning" my question is where is the mileage wheel located on this printer. Tried looking around on the web and haven't found anything other then a description of it function. I'd like to know generally where it's located to visually see if it malfunctioning. The printer doesn't appear to be clogged, if I clear the error it resume printing however will stop occasionally when the error returns. Lastly, I know I can reach out to customer support and probably will, I just was curious if the community had any insight.