I have a Pfaff 7570 that I have had several years (10 or more) and I leave my machine on for hours at a time. The only time I turn it off is when I am done for the day. I have replaced my bulb 1 time. Yes, it was expensive (over 7 bucks at the time), but I have also replaced other machine blubs with the same type of bulb used in the auto industry.... They are the same type and work just the same....