May I add a warning to those who have one of the latest Bernina 570/80QE - well in fact any of the Bernina machines that have these feet with sensors on. As well as cleaning out around the bobbin area, feed dogs and the needle, up by the needle in the harp area you have some sensors, you will need to take a mirror to see these. These sensors need to be kept very clean and clear of fluff and debris otherwise when you go to use the machine for say buttonholes the long buttonhole foot has something on the side that looks like a round globe – this is the sensor, and thus will react with the inbuilt sensor up by the needle. It is possible that you may have other feet that has an extra piece, maybe square up where the connection piece is for the foot to fit on to the machine’s shank, and in this square there may be two or four little globes which are sensors.
If fluff and debris accumulate and stick to the inbuilt sensors, then in buttonholes the machine will play up and not stitch the buttonhole out properly – guess how I found this out. So such a simple thing to keep clean, and I have some cotton buds and a piece of a micro duster that collects and holds dust right by the machine. My kind Dentist gave me a couple of long handled plastic dental mirrors, and these are just for keeping an eye on the inbuilt sensors.