Very anecdotal (just the experience of me and my friends, who have a total of 5 new sterns between us), but I think there's not much maintenance. These things are made for commercial settings so they're pretty durable. One of mine had a bolt fall out of the auto plunger, which I screwed back in. When it fell out again I added some loc-tite and it has stayed in since. No other issues. If you're into DIY at all, they are VERY easy to access for repair. The playfields flip up, they come with technical manuals, many parts are generic, and all parts are pretty easy to find.