Sorry, can't help with the possible imbalance. Have you got an instruction manual that might give you the correct settings for gathering? Maybe contact Elna's helpline or check out their website for the correct settings.

Another thing is are all the needles from the same packet? Is it possible that you have got a faulty batch of needles? This happened to me once, very frustrating but when I got a different packet of needles, they stopped breaking. I assumed that there was a fault in the metal.
Hmm, that's a good idea about the needles. I will try that if I have to go into the store.
The machine has a guide for gathering, but it doesn't gather enough so I have adjusted the tensions to make it more gathered. I feel like it should be okay, but just thought I'd see as a last resort if that could be the problem.
This is the 3rd Overlocker I have had. I've already had 2 others replaced for being faulty! All different problems, mind you, so not like I'm doing something wrong to all of them!
I will have a look on their website for troubleshooting.
I just want it to work!!!!