Lower Unit Install - Water Pump Drive Shaft Froze

[retrojeep]

I just got my lower unit today and was inspecting the drive. The lower until shift in forward/neutral/reverse fine by turning the prop shaft, but the water pump drive shaft does not rotate. I can feel the gears try to engage, but it does not turn.

I'm worried about installing and trashing out the lower unit if it was assembled incorrectly.

Thoughts???