Thread breaks

In Every Needle or just 1 needle.

burr in the needle I would guess. easy fix.. replace needle. I turn mine about 10 degrees off center so not straight facing forward but just a little to the right. old school but seems to help.

They are most likely right on the money with the problems.

One of the other possible issues could be that timing is off by a hair.

On one of my 4-heads the hook distance and timing can be off by half a mm or less or half a degree and it will cause issues on a single needle due to minute variation in needle alignment.

For example on a 15 needle head you might have needle alignment specifically distance from the hook variation that might look like this.
Note the lines are mid average distance.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
- ^ - v - - - - - - - ^ V - -

In that instance you would need to time and tighten the gap between the hook point and the needle using 14 or 4 as they are the closest to the hook point, if you try to tighten the gap on any other needles you would most likely break needle 14 or 4, as well if its not tight tollerance against those needles than, needle 3 or needle 12 might have issues where the hook point is scraping against the thread instead of catching the thread and you get sheering.

the alignment did not come out right but the number of symbols are correct.

Then it's that needle or Thread.