I don't have experience with paper tape. From the description it sounds like the oils dissolved the rubber by acting as a solvent to the natural oils in rubber. If this is the case, you could try something that can act as a solvent to the oils, such as acetone. You'll have to test against a sample tape, and don't assume that the acetone or other solvent wont remain in the tape and cause damage in the future. You should try to find a way to copy new paper tapes or transfer the data to some other medium. How much data is in the exposed tape that was damaged? Don't they have leaders with no data on them? Did the damage extend into the layers beneath the surface? I'm assuming that the tapes were rolled up and only the first few inches were damaged.