i struggled a lot with this a few months back. Best was eucalyptus oil which I purchased from supermarket after googling the topic . But also stand the board in the sun on its side so the glue gets warm, just about 10 minutes in sun will be enough.Then get a slightly rough cloth like a piece of toweling. But some eucalyptus oil on it and rub like crazy. Board smells good after treatment. Let me know how it goes ???? Also heat up the rails a bit in the sun when removing the old tape.