Electro-hydraulic rear preload adjuster on 1200

Every bike I have owned with a hydraulic pre-load adjuster has quickly lost the first part of its adjustment. Let me explain. My Honda ST1300 is less than a year old but the hydraulic adjuster knob is just slack (has no effect on the preload) for the first 8 turns out of 36 (22%). That is now under a warranty claim but the problem has been universal. It even happened to the manual hydraulic adjuster on an Ohlins aftermarket shock fitted to another bike. As my Multistrada 1200 is 20 months old, I thought I would check the action of the electro-hydraulic adjuster expecting to make a warranty claim. All credit to the Ohlins system on the Ducati, the preload still started to move (increase) from setting 1 up to 16. In other words, it was perfect. I'm impressed! The problem normally encountered is that, because of the very high pressures, the seal on the hydraulic ram slowly leaks a tiny amount of fluid past it and reduction in the amount of fluid available reduces the travel available. Obviously the fluid goes somewhere and that has to be on the wrong side of the ram. There's normally no way to easily replace this lost fluid. It has occured to me that the best fix would be a one way valve allowing the leaked fluid to be pushed back where it belonged when you backed off the adjuster to zero. Since the Ducati/Ohlins system has retained its travel perfectly, anybody know if they use any such one way valve or how else they maintain the travel so accurately?

 

Thanks!