Elna 664 Bottom Thread loose - Baby Lock Eclipse Serger

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https://www.google.com/search?q=threading+my+Elna+Serger

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Elna (model) manual

Here is one

ELNA 664 Pro Instruction Manual - ManualsLib

https://www.manualslib.com > ... > 664PRO -
View and Download ELNA 664 Pro instruction manual online. 664 Pro sewing machine pdf manual download. Also for: Elna 664.

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Loop and nesting on wrong (bottom) side is usually low or zero tension of top thread. Can also be uneven feed of top thread. If unsure whether top or bottom thread try a different color top thread.

With a horizontal spool, be sure the spool cap is larger than the spool and that the thread unspools falling forward over the top of spool and not towards the rear (see user manual).

Test top thread tension... with foot up set tension to 4 and make a long steady pull. Then lower foot and make another long steady pull. Note difference in zero tension (foot up) and tension setting 4 (foot down). If no difference then make sure there's no debris or thread stuck in tension discs.

You can make a long steady pull of bottom thread and it should have a tension similar to the top thread with tension select at 4.

Comment here for further assistance.

Hopefully, it was recently serviced. Take it back and have the technician take another look at it. Do NOT unthread it (just clip the threads below the thread tree) when bringing it in so the technician can verify it is threaded correctly and also see where it may be hanging up.

Manual:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiwheb74__XAhVN0GMKHbMuCv8QFggqMAA&url=https%3A%2F%2Ffiles.tv-sewingcenter.com%2F2015%2F03%2FElna-664-Serger-Instruction-Manual.pdf&usg=AOvVaw0Dq_m0xuI-9tPhZbrA2KGU

1 Accessories catalogue (last page)

Needles Organ Type 15X1SP 10pk

Elna United States Accessories Sewing accessories Needles

When your bottom thread is messy it is the top thread needing adjustment. Your machine may not be threaded properly and the thread may not be sitting correctly between the tension discs.
Check to make sure your machine is threaded correctly.
Check thread between the tension discs.
After checking, adjust the tension (tighter) and do a test. If it is still messy add some more tension and do another test.

Tension. When you thread your machine, be sure the presser foot is Always Raised. Also, when threading, give each thread an extra little tug when threading the tension disk--sometimes it will pop when it seats. If thread is not seated, the tension will be off.

Here's a manual:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi0stTKiYHQAhVSwGMKHd11DeIQFggeMAA&url=https%3A%2F%2Ffiles.tv-sewingcenter.com%2F2015%2F03%2Felna-664pro-serger-instruction-manual.pdf&usg=AFQjCNGXdDnztzPbefZ57kdagHOAXPoBSA&cad=rja


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Make sure it is installed correctly (all the way up) and threaded correctly. Generally, when something goes haywire, it is best to remove all the threads, RAISE the presser foot, and rethread completely from the beginning. Also, grasp the thread above and below the tension disk and give each a little tug to verify it is seated properly.

Then set the tension dials to the midway point and test. If the needle continues to strike, then it may be out of time and need adjustment.

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rethread the machine completely, using every thread guide
change the needles
make sure the tension is adjusted correctly
and if these suggestions don't help then the machine needs to be checked