Juki MO-644D Mechanical Sewing Machine - Answered Questions & Fixed issues

I imagine that it is the mechanical knee lift that you actually lift with your knee? Sometimes the screw that holds the knee lift rod comes loose a little and starts to slide in the holder. Sit on the floor where you can see the underneath of your table and use a wrench or vise grip to loosen the bracket that holds your knee lift bar with the pad on it. Move the bar to the left and retighten the screw and I think you will be ok. Sometimes if there is too much oil in your pan or you have moved the machine and some of the oil spilled out, a little oil gets out of the pan onto the bar and makes it start to slip. If that doesn't work we'll try something else.

I found the instruction manual for your serger on eBay. It is item # 160454752052

With some sergers, but not many (singer 14u64 comes to mind), the top of the stitch will be an overedge that mates with the right needle thread, and the left needle thread will appear as a separate straight stitch. When you look at the underside of the stitch, the overedge will go all the way over to the left needle (the full width of the stitch). This is normal if you have this type of machine. Another stitch some sergers do (2/4 thread sergers) is a 2 thread chain thal looks like a lone straight stitch on both sides, and a 2 thread separate overedge.

As far as the threading of the takeup, it totally depends on your model. Always post your model number when you have questions as sergers vary greatly in design.

Attachment method is not correct. Owner's manual shoud tell you how to do it properly. No Owner's manual, try manualslib.com if they have it. or the MFG website.

Have you installed new needles recently? Also, sometimes old thread causes a problem,. Or the needle size/thread size are not compatible.

Here is the Manual: JUKI MO 644D Instruction Manual

A overlock machine helps you clean finish the seams. You can do many things with a overlock It can cut your sewing time down. The sewing machine is good for many thing too,Mostly the construction of the garment. I have three machines. A indstrialstraight stitch, a home machine and a overlock.Al for different tasks.

ordinary drop feeds are not suited for sewing leather,ideally a needle feed or machine with a walking foot mechanism is best suited.if you are stuck with this machine only,there are a couple of things which may help.on some of the juki ddls there is an adjusting screw and locknut on top and in the middle of the arm of the machine .turn needle by hand wheel to bdc and loosen this screw and turn clockwise slowley! this will raise the presser foot very slightly,so when the feed dog is at tdc it can improve the feeding . spear point needles are reccommended also. one other idea,but you need a qualified mechanic to do this is to alter the feed timimg slightly on the eccentric on the top shaft.as the needle is entering the fabric,slow the timing down so the needle enters the leather just as the material starts to move. hope this helps! cheers kev w 07725903110

1. . re-thread your machine with a rainbow of colors. (important that you remove the existing threads if you are not sure it is threaded properly.) make sure you are lifting the presser foot while rethreading.
2. Sew a good 6 inches.
3. Look to see which threads are the offenders and tighten the co-responding tension knobs a little.
4. Sew another 6 inches. Examine the result. Adjust tension again if needed.
5. Work this way until you have the stitch balanced.
6. Finally when your stitches are perfect. clip the threads at the spools in back. And tie on the coordinating colored thread for your fabric.

Get used to this procedure since it is common to have to adjust tensions when you change fabric. Good luck!

hi there
please send your email address i will send to you service manual for this machine.
best regards
ashraf abozid
[email protected]

Sounds like as the machine builds up friction from extended use, some vital part is lacking lubrication and is seizing up. A good service person will remove ALL of the covers and thoroughly air clean and oil every moving part. Sometimes these dry points are hard to find and patience is required.

You can get a sewing machine oiler with a long applicator and put a drop of oil on anything that moves, but over oiling can be messy.

Hii try to attach PDF file for how to adjust top cover thread spreader and how to adjust looper timing but the upload only support gif-jpg-png file,please email me to send PDF file to you.BEST REGARDS

http://www.jukihome.com/downloads/manuals/MO655_InstructionManual.pdf p. 46 of this pdf. Top blade rarely needs replacement, but lower blade works like this. I highly recommend taking good closeup photos of the machine, front, back and side view, of the knives before you start swapping them out. See, e.g.: http://www.picturetrail.com/sfx/album/view/24107038

It may be your timing is off on the loopers, a thread guide or needle guide can be out of place or even incorrect tensions can cause this symptom. This is not something easy to fix with on line advice. You need an expert.

hi there please see link to download user manual for JUKI MO-644D http://www.juki.pl/support/HSM/Manuals/MO-654DE_manual_UK.pdf and you must made upper and lower knife very close to cut material correctly. regards ASHRAF CAIRO - EGYPT [email protected]

Sometimes using a larger needle will help. That is if it's shredding the thread when it goes through the needle which causes it to break.

You have to be shown physically

try having longer thread tails and keep them pulled to the back of the serger

Contact this person and ask him. http://www.raichert.com/

Good luck. I found a replacement part for one of mine on Ebay. Just search for Used Juki Serger for parts. Maybe you'll find a 644D for cheap enough that you can scavenge parts for a few more years.