about to throw serger out the window!

I am trying to use my elna 744 to do a coverstitch. the left needle thread keeps breaking. I have rethreaded, adjusted tension, changed needles, replaced the antenna and made sure it was all aligned. I haven't used machine in ages and am wondering if I'm forgetting something. It is so frustrating - any help welcome!
Ax

I'd take it to your dealer.  Sometimes they can help you see something you're missing.  Once my serger was being super fussy and I took it in, thinking that it needed to be serviced and the lower looper thread wasn't really in the tension disk and that was it.

sometimes when the needle thread keeps breaking it's a good idea to check about burrs on the needle plate
could you have the needle in backwards?
and sometimes when a machine has set up for a while it's good to have it serviced