I removed 2 manual MC rods recently. In both, I had to hold the MC in a vise, put a socket extension thru the rod hole and beat real hard with a hammer until it popped out. An O-ring secures the tip in the MC piston, and gets hard. It might be a square ring (never found enough pieces left to tell). Look in the faucet seal section of the hardware store for something to work. I expect the rubber just keeps the MC from rattling. The rod can't come out of the piston once assembled in the car.