My 4110 has a total of 3 hydraulic filters. The first is the metal screen in the trans. case on the left side - it is held in place by 1 bolt and slides out to clean. The second filter is the spin-on filter that is located above the rear axle on the left side, clearly visible looking at the back of the tractor. The third filter is the power steering filter which is a cartridge type filter in a large metal canister mounted under the tractor on the right side, once again you can't miss seeing it. I find it is easiest to drop this whole canister and disassemble to change the filter and clean it out good, without getting a bath of fluid.