Shew! Don't run any of that nasty, dirty thread through it, you won't be doing it any favors.
I have a newer Kenmore badged Janome which has been a great machine. I got it on closeout at Sears for 50.00 in a sealed box, and a 1980 Juki MO103. The Juki is basically an industrial machine with a motor attached. It weighs a ton, has no light and will chew through anything I can fit under the foot - it is a mean little sucker
Once you get the machine cleaned up and oiled you'll have a good serger. Those old girls were built to run. From the look of the blade set up it may very well be a Juki machine.