Lint in upper thread area
I was having lots of tension trouble FMQ this winter with my BL crescendo then the bobbin started making an unusual noise. The machine upper sensor started even to not recognise thinner thread. Into the dealer it went. Picked it up today. The upper threading area was tightly packed with lint and the bobbin had a nick in it. The cutter also had to be replaced. The technician said maybe the bobbin had not been seated right at one time. I use a lot of connecting thread and star thread for quilting because I like the looks of it but do need to clean under the throat plate every bobbin or 2 change. There is no way to clean the upper thread area out at home. The machine was cleaned and serviced last August. I am going to switch to Isocord and Aurifil. I still can use the other thread with my BL quilters pro that I've not had a problem with it.