As Marc said, the cap screws at the top of the cylinder requires a specialty tool (spanner wrench) for proper removal. When I was younger and dumber 8) , I tried every version of home-made tool solution for these cylinder cap screws only to bugger up all of them and make the job 150% tougher than it shold've been. Once you buy the right size spanner wrench it's a cinch! (FYI the China-made cheap ones from Harbor Freight are NOT sufficient). Then you just replace the seals and reinstall in accordance with the manual.That said, the tops of these T&T tilt pistons tended to rust frequently, but the rusted end itself retains plenty of strength and is little more than an eyesore until they rust all the way through to the plastic sleeve in the center. There's usually no functional disadvantage to leaving it be, flaking off all loose rust that you can, and treating with naval jelly, ospho, or other rust treatment/converter to get back on the water and save a few bucks. If you've already bought the piston though, then get or borrow the spanner wrench and have at it! If I can find the purchase confirmation from the spanner I bought a few years ago I'll add it to the thread.