One Wheel Won't Spin?
The left wheel, the one under the power button, only spins weakly/intermittently. If you stop it with your finger it provides no resistance at all. I think the wheels seem to be turned not by their own axles, but rather by little knurled rods above the wheels that contact the tires directly. The rod above the broken wheel seems to spin somewhat erratically compared to the working one. If you stop the wheel with your finger, that rod continues spinning. So my thinking is that it's not pressing against the tire as hard as it's supposed to? Maybe it's bent, or maybe there's a spring meant to be holding it there that isn't.