I have a EUCLID R35 that keeps losing oil from the canisters for the rear brakes. Anyone know if there is a check valve or something allowing the oil to return to the storage tank? There is no obvious signs of oil on the rear tires where I would assume oil would be escaping if that were the problem. If anyone has any ideas it would be appreciated. It generally happens over the weekend while it sits and when I fill them it will normally not drop the pins through the week. (sometimes takes a couple fills to hold level)