Ramp Agent reported a power stow baggage conveyor malfunctioned and continued to move forward; striking and damaging the aircraft.

Narrative

My crew and I were walking back from D23 to go to D18 to support unload. My Crew Chief told me to get the power stow from D17 and drive it to D18. I went to try and start it up but could not. My crew mate came over and helped me out and he and I noticed the neutral had to be held upright to start the machine. I then drove it to D17 to the front belly to start unload. I pulled up; stopped the power stow and got off. As I got off we all saw the power stow continue to slowly move forward eventually making contact with the cargo section of the plane. I quickly hopped back in and reversed the stow away and we then called management told them what happened. I realized after I got off the power stow it was still moving forward and saw it make contact with the plane. The event occurred by me making contact with the plane with the ground machine by accident. I reversed the power stow away from the plane; then Crew Chief called Management and let them know what happened.Suggestion: Maybe not swap gates so much and stay on the gate given.