Bobbin thread not trimming

[Jackie]

The bobbin thread on my XT does not trim about 95% of the time. This just started about 3 days ago. I did not have a thread jam or anything else go wrong before it decided not to trim. I cleaned and oiled the rotary hook and trimmer, changed the bobbin case, been thru about 2 dozen bobbins. Could it be the hook timing is off?
nfused:

[Redina]

I was having a similar problem but replacing the very dull knife has solved it. Have you tried that yet?


Redina