I just gave away my best 503 recently, with a big Copenhaven cabinet full of all the attachments and doo-dads. It was so much fun to get it working again and to hand it off to a young woman who wants to sew. There's nothing like these old gals for toughing through a newbie seamstress.
You're going to have a wonderful time with it and you don't have to worry about breaking it!
Remember to keep the race clean, clean, clean - that's the only real vulnerability I've found in the 400/500/600 machines - a little
tiny blob of lint can really foul things up.
Have fun and make beautiful things!