I have a 700 too (700K), although the carriage feels quite substantial or 'heavy', it actually moves very easily. Regarding the wheels/cogs at the rear of the carriage, I think you are referring to the memory drums? Mine are very free moving, but I had an experience with another Knitmaster machine recently (a Zippy Plus), where the drums weren't moving at all. Another member of this board posted some helpful info... but by the time I read it, my friend had sent the carriage away to be repaired. It cost around £50 with postage.