the used 300T I test drove had a buzz that clicked in at med/high volume on sustained low notes. Store had tech look into the issue, and they say it was a faulty transformer. If they fix it (repair/replace?) any reason not to re-test/buy? (asking $700 - seems a little pricy for a used one seeing I got a quote for $950 new at another store). Not sure if I am better off looking elsewhere. Any things to look out for?