We receive many many many questions about this issue every day -
"Why is my stitching bunching up horribly here....etc."
First - if you have threaded the machine in the correct order, Dial#3 Upper Looper, Dial#4 Lower Looper, Dial#2 Right Needle, Dial#1 Left Needle, and are sure no threads are crossed and they are seated properly in the thread tension disks...
Presser foot should be down when trying to serge the chain.
Threadtree is all the way UP,
Visually inspect your needle plate and verify that the chaining forks are pointing straight back toward the presser foot and still attached securely.
Remove the presser foot to see the condition of the Needleplate more clearly if necessary.
If they have broken, and you must replace the needleplate, it is considered a Warranty Repair if you purchased your machine less than 12 months ago. Amazon, Brother 1-877-276-8437, and Costco are excellent about taking care of this.
The key is to not force the threads or fabric, particularly in a jam - sideways ----- working "with" the equipment pull straight back (behind the presser foot) and most folks will have their original needleplate last a very long time.
DO NOT ATTEMPT TO USE PARTS from the old needle plate with the new one.
The new one has been re-designed and does not have the same parts.
This is the most common reason folks thing they have purchased the incorrect part - because they expect the new one to look like the old one.
The HoneySew one on Amazon is frequently bought by our members and they have had good results. Another company on eBay sells the part and we have not had any reports of problems with that one either.
Where to purchase your replacement needleplate