A paper conservator colleague who often deals with pressure sensitive tape suggested that you check to see if the adhesive is still tacky and flexible, or if it seems dry and brittle. If tacky, gentle heat might be a good option to remove. If that doesn’t work, a solvent chamber might be necessary. If brittle, gently separating with a microspatula might work. Unfortunately, after 10 years against tape adhesive and cardboard, the patches likely already have a stain present, but hopefully you can find a removal option that doesn’t leave additional residue. Let me know if you need additional information!