Cooling water issue

[bowhunterick]

I'm recently retired and getting time to do some extra things that I couldn't find the time to do before. I'm admittedly a novice with outboards. I have a 1969 Merc 7.5 outboard that's been in storage the last 5 years in my basement. I took it out a couple weeks ago and started it up but noticed water was not coming out the side cooling hole. I ordered an impeller kit and replaced it today, when I started the motor up after the replacement I had water coming out of the side hole while I was in Reverse but in Forward it sputtered out, at best, it really was almost nothing. I noticed when I replaced the impeller I could turn the prop backwards and the shaft would spin but when I turn the prop forward the prop would make a clicking noise - the shaft would try to spin but it wouldn't make full revolutions without the help of my other hand. While testing in the water, both Forward and Reverse engaged the prop fine. Any ideas why water isn't coming out of the side hole when running in the Forward position? TIA