my B-T1501 stopped trimming the threads this morning and I have not
been able to find the cause. The blade is moving fine but it just does
not cut anything. As a consequence, every time there is cut command I
get the 206 error, but it goes away if I manually cut the thread with
my scissors.

I tried to adjust the blade tension without any result.Remove your needle
plate to be able to fully inspect the knives. Under the needle plate you will
find a silver articulationg knife and a black knife that
has SWF engraved on it. Look at the leading edge of the black knife and inspect
it for any burrs or nics. Use your thumb nail to detect if it has a nic on it.
If it does then it will have to be replaced.

If you swing the silver knife out from under the black peice and loop a peice
of thread around the front of it, push it slowly under the black peice all the
way and see if the thread trims, If it does not then the angle of the black
opeice is not set correctly and will need to be adjusted. It would be like the
screw comming loos on a pair of scissors would not allow you to cut paper, the
same lies true with that black peice. If the angle or height has changed then it
will not cut at all.

For both of these scenarios I would highly recommend either you send the knife
block in for adjustment or if there is a nic in the black peice then I would
also suggest you send the knife block in for repair, as setting the angle and
height of that black knife has to be set exact. A trained technician could do
this in about 20 minutes and without ever seeing one you can very well be at it
for days. Setting the angle and height and then remounting it to the machine put
the needle plate on and test the trim. If it fails then you got to remove it
again and try a different setting. You can see how this would build to a
frustrating matter real quick.

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