The cord of my adapter (sp 303) has a short in it. I used to be able situate it to where the cord wouldnt move and then id be able to turn my 303 on. Not anymore. Its a 9v, i was given a 12v, it fits but will it mess my machine up?

maybe. depends on whether it has protection against too much V or not.. you should really only use 9V

Actually many devices need a couple more volts than they say. If you have a voltmeter you would be surprised what an adapter that says 9V or 12V or whatnot will actually put out. I have measured some with my multimeter and read up to 17V on a 12 V adapter. 13V on a 9. Most consumer grade electronics made in the last decade have some protection. Usually a voltage regulator to take the over voltage and regulate it to a steady output.

That being said, find a 9V adapter. You can find one at any thrift shop. Just make sure that it has the right pinout. Ie; center NEGATIVE(at least for my 202). Also you can buy one of those adjustable wall warts. However be warned they are rather cheap usually and you should use your meter to measure what anything you buy is putting out and confirm that the center is negative(at least for my 202, make sure by looking on your device!)

a 9v 300ma or 500ma adapter do the trick, normally...

Radio Shack. Enough said.