I had a very hard time removing the tubes from mine. The trick for me was to clean the top of the tubes with alcohol to remove any oils that might have been present and wear clean nitrile gloves. The increased grip due to the clean tubes and the grippy gloves made it possible, but it still wasn't easy.
@dekay That vacuum tube puller looks pretty cool and will probably work. There should be enough room around the tubes for it to fit.