I found out it's easy to break the arm connected to the feed-dog lever. On my sewing machine (Janome) I can lift the feed-dogs a little higher if I push it higher again. I tried that with this serger and it broke. I didn't push it very hard.
It is a metal bar held in a plastic gear. We took it apart to find that out. I tried gluing it with hot glue gun, that worked for a day. We glued it with a type of epoxy last night. It takes 24 hrs. to cure so I don't know how well that will hold but I will probably find an arm to order.
Just letting you know so you don't try it. I was trying to get more clearance to get a mirror under it while inserting new needles. ooops (This works great on my sewing machine, because then I can see the holes to insert the needle.)