Singer 514 Stylist Thread Breaking

We've had an old Singer 514 Stylist in the basement for about a decade (received from my husbands mother, who got it from her mother, who got it from her mother). Recently brought it out to make masks for covid-19. The machine is fantastic except the one little problem of the the thread breaks often. Tension settings don't seem to make a difference I tried all of them, checked all the usual stuff like if the thread is properly routed etc... no luck. There seems to be a buildup of "fluff" behind the needle after sewing for a half hour or so, not sure if that's common. Trying a new needle this weekend but not sure that will fix the issue (Needle is a No. 11 and using standard thread on cotton fabric). Also strangely with the needle in the left position the thread seems to break far less often. It does probably need to be oiled, getting that on the weekend to. Any thoughts or tips would be appreciated.

The machine is fantastic except the one little problem of the the thread breaks often. Tension settings don't seem to make a difference I tried all of them, checked all the usual stuff like if the thread is properly routed etc... no luck. There seems to be a buildup of "fluff" behind the needle after sewing for a half hour or so, not sure if that's common. Trying a new needle this weekend but not sure that will fix the issue (Needle is a No. 11 and using standard thread on cotton fabric). Also strangely with the needle in the left position the thread seems to break far less often. It does probably need to be oiled, getting that on the weekend to. Any thoughts or tips would be appreciated.

Check your bobbin tension as well and use a better quality thread such as Mettler or Gutermann; there are probably other top-notch threads on the market. Yes, try a new needle AFTER YOU HAVE THOROUGHLY CLEANED AND OILED THE MACHINE.

If you had a car and left it sitting in the garage for 10 years you wouldn't expect it to run like one right off the showroom floor, would you??