DH bought me an 850 on ebay, it was new but no warranty but good price. It has problems with C&C threads. My feed dogs creep back up gradually. No help from shops that sell and I understand to a point but I still buy accessories and they aren't cheap. My spring foot makes noise like it is hammering is this the thread? I have been breaking several needles per quilt, try and rethread frequently as it seems to tighten in the upper tension. Any answers. Oh yeh, a friend bought an 830 and the folks where she bought it aren't helpful at all so guess it makes no difference where one buys it except for warranty work.