Did you remove the aluminum block on the very bottom of the cylinder that the hose connects to? It has 4 screws that require a 12 point 1/4" socket. As for leaving the cylinder in and replacing the seal, it can be done but is very difficult. **** a sharp screw down into the seal may make it so you can pull the old seal out. If not the chain down and pull the lever will work. The problem will be getting the new seal in. There isn't enough room to push the seal in without it rubbing along the threads that hold the cap on and it can damage the new seal. There is a special tool that is shaped like a funnel that is used to make the installation easy. You may be able to take some thin feeler gauges and install them all around the outside of the new seal to help install. Be careful, this is about as dangerous as it gets working on forklifts.