It will likely be more expensive to repair a damaged transformer like that than it will be to replace it, even if the new part is custom-built to do the job. It will be handy to get some voltages from the amp that works, and its likely that you have something else wrong with the amp- its unusual for power transformers to fail on their own.
You might want to talk to Jack Elliano at Electra-Print http://www.electra-print.com/
You might want to talk to Jack Elliano at Electra-Print http://www.electra-print.com/