10UJ13 Vintage serger by singer
 

This serger belonged to my MOther. I cannot believe it is as old as its serial number indicates #31259. Any info?

Do you still have your serger? I recently purchased the same model and was also wondering how old it was - 1970s?

I still have the one I bought in the early 70's and it still works...

I have one my landlord gave me after his wife died but the left needle keep unthreading and if I try sewing with just the right needle it comes unthreaded. Can anyone help me figure this out?

Do you have a manual for your machine? I downloaded one from https://www.manualslib.com/manual/69...er-10uj13.html I initially thought that maybe it was that the needle tension was too tight or that the machine was threaded in an incorrect sequence. After browsing through the manual, it appears that one needs to change the crank lever somehow, depending on if you are using either the two thread overcast or two thread chain stitch.

Sorry, I can't give a more definitive solution.

Janey - Neat people never make the exciting discoveries I do.
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Something that might be influencing the thread breaking is that the needle is not inserted correctly. It looks like it takes a round shank needle. There is a member of our Colorado Get-together group, that has worked with industrial machines that use round shank needles. She prefers them and mentioned that in an industrial setting that they work better so that the needle can be adjusted better to the hook on a variety of machines.

Janey - Neat people never make the exciting discoveries I do.