Replace the check spring on a Singer 15k sewing machine
Modern check springs - the wire that sticks out of the thread tensioner and forms part of the top thread tesion system - have an open shape. It is easy to catch the thread under the hook. Older models had a crossed wire design. If the thread jammed where the spring wire crossed itself, it would break. This is immensely annoying.
If your check spring looks like this: Bad check spring design replace it with one that looks like this: Good check spring design
My replacement check spring came from and cost about £3 in 2007.

Before you start dismantling any part of your machine, read the dire warnings page of this website. You can click through to the warnings page here:
You will ned the following kit:
  • Screwdriver
  • White lithium grease
  • Kitchen roll
Picture of the tools in the list
Dismantled parts in order Undo the finger nut and remove the end plate, the beehive spring (the conical one) and the thread tension plates.
Then undo the 2 fixing screws at the back of the machine and ease out the threaded rod and check spring. 2 screws that hold the assembly into the face plate
New check spring in place Take the old check spring out of its slot and insert the new one. Check spring tongue in its grooveSquirt plenty of lithium grease around the spring and the cylinder it slots into.
Poke the rod back into its hole, which looks like this: Hole the centre piece fits into
Slide the thread plates back on to the threaded part of the rod, then the beehive spring, end plate and finally the finger nut. The job is done. Before your next sewing project, take time to check the thread tension because this dismantling operation will have messed it up.
It is possible to buy whole check spring assemblies with an enclosed beehive spring and numbers to indicate your tension which claim to fit a 15k machine. They are sold by, the link is given above. I'm quite happy without numbers and I'm not convinced the bit that goes into the machine head plate is the right diameter so I've never bothered to investigate. This paragraph is just so you are fully informed.

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