I have a manual log splitter that uses a 10 tonne bottle jack, operating horizontally. After a few years use it started leaking due to worn O rings in the 2 hand pumps (for fast and slow ram movement). I had trouble getting new O rings as they are thicker than normal for their diameter. It did come with a small bag of spare parts but the O rings were thinner than the ones in the machine. The slow pump leaked first and I fixed that about a year ago by cutting a larger diameter O ring of the correct thickness and using superglue to join the ends. A week or so ago the fast pump started leaking and this time I did manage to get a slightly thicker O ring than the one in the repair kit. This did fix the leak but new symptoms started. Now when I use the fast pump the ram advances but returns when I release the lever. This means I only get one stroke. It still produces enough force to split logs. The slow pump is also affected but not as badly. It partly returns but still advances with each stroke so I can still use the machine. I'm told it could be a ball valve that is not seating properly but I don't know how easy such ball valves are to get at? I tried bleeding the jack by pumping each hand pump with the release valve open. This made no difference but I did notice that pumping the slow pump sometimes caused the fast pump lever to move. I did buy a new bottle jack of the car workshop sort but it does not look to have enough travel for use in the splitter. It would also need a new part made to attach the end of the ram to the retraction spring assembly. I'm now thinking of replacing the bottle jack with a standard hydraulic cylinder and separate hand pump with reservoir. Am I right in thinking this could do away with the retraction springs by having 2 way hydraulics?