This makes it easier to remove the stitches as they are fewer and longer.
By doing so you won’t notice the stitches as much afterward.
If thread bunches up again immediately after you start sewing and you thoroughly cleaned the shuttle race, then needle and shuttle hook synchronization may need to be adjusted.
Adjusting the needle timing typically requires service by a technician, who has special tools to synchronize the shuttle hook with the needle.
Even if you cannot see any burr on the needle try to exchange it for brand-new needle before you move on at this point.
This can sometimes happen if the needle hit the bobbin case.
Clean lint and debris out of the shuttle race; they can prevent the needle from hooking the thread, resulting in thread bunching up in the shuttle race and jamming the needle.
Cleaning the shuttle race may prevent the sewing machine from locking up again once you resume sewing.
If the machine doesn’t respond properly to the stitch length setting you might have to take it to the shop.
But first, you need to make sure it won’t stitch the buttonhole correctly as well.