I presume you have the decision to deny the claim in writing. I would respond and ask if they have appeal or review procedures for warranty denials, and if they do, take advantage of them. If there is anything you do not understand in the denial, ask them to explain. For instance, what is the basis for denying the claim for "sheared" gears. Ask for specific citation to the warranty. Oh yeah, read your warranty cover to cover-especially drivetrain stuff.
All of the above letters are in writing and copies to SOA customer service and maybe even the Maine Better Business Bureau--keep your own copy as well. I would not hire an attorney as it will cost you too much for the amount at issue.
You might even call shops like vermont sports car or Patrick Richard's shop in CA. They may sell the trannys they pull out of cars before they make into rally cars.
You could file a claim in small claims court for the repair amount, but I suspect the warranty has an arbitration clause.
Good luck and remember sometimes the squeaky wheel...... you may have to be real squeaky though--but professional not angry squeaky.