I agree with above. Another technique you might try after your have heated the system to soften the thermal paste is this. Of course you will NOT have lifted the CPU lock lever. As an initial step, grasp the pump unit and try to TWIST it gently. Do no twist hard, and do not pull straight up. The CPU will be held securely in its socket, and IF you can twist it, that will break the bond between CPU and pump. THEN you can lift carefully.