You'll definitely want a DMD game for your first pin (because the self-diagnostics can help point you in the right direction sometimes).

But you'll definitely want to learn how to repair the machine yourself (or you could end up paying as much on repairs as you did for the machine).

Try and buy one from a local hobbyist who's extremely thorough and has gone through the game with a fine tooth comb.

If you can't fine one locally, it's worth it to pay the shipping and get one from a forum seller with a great rep who's already gone through the game.

Neil