i got a whole lot of green stripe pads 21" cheap from the paragon microfiber site in a sale ... as they are made from two pads sewn together i cut them in two as the thick pad dosnt work well on the orbital. Sometimes i put a scrub pad on it .
Imbalance? dont think so , although i was using it mostly in hotels on either wool or nylon carpets ... not ideal , id say the resistance didnt help the bearings. I might find the perfect commercial job for it and get enthusiastic about using it again in the future .
Did u get one yourself ?