Dropping the Lower Unit on my 1993 Yamaha 9.9

I am trying to change the water pump on my 1993 Hi Thrust Yamaha 9.9. I believe the model # is TEXHR. I have removed the 4 nuts under the cavitation plate and the zinc anode over the prop. The lower unit will not drop. Am I missing a nut or is it just frozen. According to the previous owner, the lower unit/water pump was never changed before.

[boats.net]

You will have unscrew nut on shift shaft to separate upper and lower shift shaft, look just in front of lower motor mounts for nut.