I'm also re-covering a plane right now and am very interested in methods for stripping. In my case the old covering left color soaked into the balsa. Xylene, goof off, and laquer thinner all were effective in breaking down this residue, but also soaked the color further into the wood. I at least got to the point where I could sand without the sandpaper getting instantly loaded. I have given up getting the plane to look like fresh balsa, and have picked out ultracote colors that are solid enough to cover the staining. I bought orange and yellow which did not cover, but cream and red are doing the job. I have an e-mail in to horizon hobbies asking for a list of Ultracote colors that cover and are not semi-transparent, 4 days and no response yet...