I hate it when the threads break in the serger.
I have problems with getting the thread to go through some of the holes in the bars in the path.
How I "deal with" that - I have some stiff nylon thread - the kind that would scratch if used on underwear - and I run it "backwards" through the holes - and then tie on the thread I want to use and pull it through.
I use the machine a lot - but rethreading it when the threads break is a major bother.