I would imagine the expense of shipping an autoharp from Oz to the states and back for repairs would be greater than the expense of buying another 'harp, in better condition. The strings, though, would be cheap(ish) to ship.

Restringing is a royal pain, but necessary from time to time. I recommend removing the chord bars (your basic screwdriver should be the only tool you need) in order to restring. And just like a guitar or other instrument, change one string at a time. The string tension on an autoharp body is unbelievable, and you want to keep it as even as possible.

When you remove the chord bars, be careful to keep them in one piece - some of these Oscar Schmidt models with the covers have chord buttons that insert into a groove on a metal bar, and they'll fall out when the cover is removed. It would be a hassle to try to reconstruct which chord is which.

When you have the chord bars off, you can check the quality of the felt. If it's not too bad, old felt can be refreshed somewhat by laying the bar on its side and sticking a pin through the felt repeatedly. This fluffs the felt a bit so its functions better - for awhile.

Good luck!

Dan