Did you mod it, or was it like that from the start? Perhaps the belt was PM's request to the manufacturer. If you search for PM-25MV you see pictures of a machine sold under a lot of names. My mill looks exactly like that, but it has a different name. The motor has a bronze(yellow metal) gear that meshes with a gear on top of the intermediate shaft (this is on top of the head and easily accessible). Then further inside the head there is this two-speed plastic gear that is moved by a dial on the side of the head. It meshes with one of two gears on the spindle.
I imagine the only place one can swap a belt in would be the very top where the motor drives the intermediate shaft. If so, is the two speed gear still plastic? Or is it metal? Perhaps the belt is enough to protect the teeth.
Edit: Actually nevermind... I found better pictures and it seems the similarities are external only. The PM mill has no speed selector and uses direct belt drive. This must be a superior system for using large cutters with interrupted cuts.
