You are Brave! - for all the machines my DH has done, he says the Pfaff 130 was one of the more difficult to deal with. Though not as bad as Viking 6000 series.
Join the Yahoo group, there is a lot of information you can look up on that site to give you a good idea what you are getting into. And the specific problems they are prone to.
parts can be very hard to come by- and if you find them the are not cheap! On the good side, there is a good market for the parts if you decide to sell them.