execution idea: one of the comment suggested fuel-like mechanic for maintenance, But i would preferred a dedicated station that will cover all maintenance in claimed zone instead (exactly How Rust's TC work) where it will consume resources you put in there. additional features about it could be option to toggle the maintenance for table/vehicle, It could also take calories which can be make into new profession dedicated to maintenance. Stuff outside the zone would simply can not be maintenance, or have to do it manually. (except vehicle)
TBH I would add maintenance to all crafting tables and machines except very basic ones. But for gameplay purposes I would suggest just to add one or several "fuel" slots that should consume spare parts. Maybe along with this when the garbage mechanics will be expanded there could be a slot that will produce junk as long as spare parts are consumed. That junk later should be dumped or recycled.
This has been added with the parts system.