@wmcihak , here is what IRS says about letter 12C ---> Understanding your Letter 12C | Internal Revenue Service.
To me your choice --- 1. Write to IRS about the letter 12C ( if you can see the ref # and/or contact/control # ) , explaining that the letter is damaged and you need a new legible version. OR 2. visit the nearest IRS office along with the 12C and a copy of your filed return.
For sure , if they do not hear from you within the allotted 20 days they will send a new request for info.