my LucyLu, is behaving badly. First let me say. I’ve changed needles, thread masterpiece and aurfil. The thread continues to break, rethreaded numerous times.  Locked out to thread needle, auto thread didnot work and then suddenly worked.  My real problem the tension is inconsistent, at times upper and then other times .lower.
Cleaned bobbin area and upper thread channel.  I’m attempting straight sewing, ( red bobbin case) nothing fancy.  Any suggestions appreciated.