There is a lot of leather (I mean tolex-works the same) techniques that can repair scruffs and scratches easily. Though I'm not sure how to repair something that drastic of damage on the top of your amp; can't be repaired. Really it's just cosmetic issue, but not the amp itself. I rather have a cosmetic issue than having the amp itself not working at all. Though you could try liquid electrical tape or just thick flex seal tape. Make sure you protect your amp with newspaper or plastic bags and support with tape of areas you don't want to get liquid electrical tape on. After repair, put tolex over it.