Nissan NS8B trouble replacing pump impeller

"I have a 1987 8 HP Nissan 2 s

"I have a 1987 8 HP Nissan 2 stroke. Trying to remove lower unit so I can replace the impeller. Removed the "E-Ring" on the shift rod, and the 4 bolts holding the lower unit. By tapping on the lower unit, I can only get it to drop by about 5/16". The whole lower unit will wiggle within the housing, but it won't move any further than 5/16". I don't want to hit it any harder. What am I missing? Putting it in neutral or in forward/reverse doesn't make any difference. Does the prop assembly need to come off first?
I picked this motor up in a trade, and I don't want to put a lot of money into it. I do want to make it right, so the next owner won't have to mess with it to use it.

Thanks for any info."

"OK, I did some more digging,

"OK, I did some more digging, and decided a repair manual is the way to go. My motor is an '87, but the manuals I see available are for '92 and newer. Would this newer book be of any use, or can I find one for 1987? I looked for either Tohatsu or Nissan for '87, and have not found one. Thanks again..."

Four bolts and you knock out o

Four bolts and you knock out one of the pins in the shift rod coupler. Service manuals are available from any Nissan or Tohatsu dealer.

"Thanks, T-G - The thing was s

"Thanks, T-G - The thing was still stuck way too tight, but you at least gave me confidence that it had to come off. It took prying with a big screwdriver to get it off. I think it was just old grease and dirt that was holding it. The impeller was intact, but was obviously old and dry. Thanks again!"