Maybe. Some hydraulic stuff can be disassembled and seals replaced, if you can find parts. Unfortunately, most of what the RV industry generally uses is not readily repairable. Not to mention, not too many the techs are capable of much more than parts swapping. Also, I am sure labor costs factor into it. It probably costs about as much in general labor to remove a hydraulic jack, rebuild it and reinstall as it does to just swap it out for a new one. Swapping parts is usally the path of least resistance. If you are working on your own items labor isn't as big of a deal.