they are not hard to work on. the hardest part to replace the seals, wipers, o rings is getting the span wrench. either get the seal kit from online companies like messicks or go local kubota. if you need it now, take it apart, leave selas in place and take whole thing to the hydraulics shop and have them match up the seals you need.
I admit that the first time i worked on the cylinder for a home made splitter , i was lost since it was already taken apart before i even looked at it. i couldnt even tell who made it, so i moseyed on down to my local hydrualic shop and told them to give me everything i need , the seals, wipers rings. they used a caliper to take measurements and went in back to get the seals for me and charged me less then 30 bucks for everything. i put it together and it works great to this day.