I have an old Simplicity Serger that I got for nothing - (can't beat that price!) It's difficult to thread but some friends showed me that you never unthread it. Just cut the thread near the spool and tie the new thread on and pull or stitch it through. If you knot is small enough it will go through and the hooks as well as the eye of the needle.
Also added a pair of pointy tweezers to my serger kit. Makes a difference if the thread breaks and I do have to re-thread it.