Need some help w/the removal of the water impeller. Here is what I have done so far. 1) Removed cover, hoses, etc. etc. Put a wrench on impeller, twisted and it spins. 2nd try - held clutch did it again but nothing. What the heck am I doing wrong?? I am a little slow !!!! but this is baffling me. The manual is not very helpful!! Thanks in advance.