I have one of these and they are really strong and reliable. It's my 'go to' machine for things my other machines can't handle, like heavy jeans hems, etc. I recently had to sew some heavy lycra for a job, and it gummed up even my Bernina 830, skipping sts... But the 503 sewed it and looked good! It was the only one, out of several machines I have, that could sew that fabric. I love it.