Don't be afraid of this serger. Internals are the same drive as so many of the Janome/New Home machines. It does not have differential feed, but that simplifies a bunch underneath. It is a solid build. Expect that it will need a good oiling if it has not been done in a while. Removing the bottom cover will expose most of the oil points.
I recently oiled and tuned one of these up and found it to be quite easy and well behaved to dial in for proper tension and not picky about fabric thickness or type.
Threading on all these older machines... I read many complaints on how difficult it is. The lower looper is the only tough part. A pair of tweezers, follow the diagram, and 10 minutes is all that is required. Just be sure the lower looper thread lays over the upper looper 'crotch' when the needles are up, ready to stitch.