I am new to pinball as of a couple years ago. My budget (and nostalgia) limited me to older machines. I started with a 1986 High Speed and then added a LW3. I had no real knowledge of how to work on machines but start with one that is in decent shape. In general my HS requires relatively little maintenance. I had one fuse issue that turned out to be a flipper button end of switch problem. YouTube is a treasure trove of help, as are the forums here.

In short, don’t worry too much, just invest a little extra in one that appears well cared for and you should avoid most major headaches and get a chance to learn over time.