LOL, they are not the easiest for a DIY fixup. You have the version with stitch length lever, and it's less prone to hickups than the knob version with push button reverse in center. It works fine, but if it get's stuck it can be a lot of work to unstick it, and cumbersome to get at the backside of it during the process. And yes, they can be over oiled, it's a joy to find one with a clean inside, often completely dry. (an Elna Supermatic I had the bottom of the freem arm swimming in oil). The one I sewed on wasn't bad at all, motor ran well, balanced stitch, the only stubborn issue was the stitch selection mechanism. It needed a lot of attention to behave again, and needed oil frequently to stay that way. I guess they are not a favorite to fix up once neglected, but up once up and running, mine stitched away happily, flat felled seams on bull canvas were no problem. I have to admit, my least fuzzy zigzagger is a Bernina 730. It's been in for service a couple of times in its' life.
Automatic must have been a fancy thing back then. A lot of models were added this flavour in their name; automatic, supermatic, novomatic, dialomatic, ultramatic,... There were hardly any one step buttonholes, but as long as a mechanism would click in place and do it's job with mechanican simplifications I guess it's automatic. Doing it manually would mean shifting the fabric back and forth in stead of a swing arm, replacing a stitch pattern cam with a a lid and screw involved. A four step buttonholer helps with getting all the zigzagging in the right place, but it is of course possible to do this on any swing arm machine with just the basic zigzag.