1966 9.5hp Johnson

Hey guys I just picked up a new to me 9.5hp Johnson 1966 model. This motor has been sitting in a shed for about 2-3 years. When trying to start the motor it turns over but won't start. I know I should probably change the sparks plugs and gear oil. I know I should also clean the carb. I'm just looking for some guidance on how to clean the carb and any other suggestions you might have. Thanks.

A service manual would be a great thing to find. What is the model number?
If the impeller is old/dried out, starting it now could send small pieces up into the cooling system. I've found it VERY hard to not try to start a new motor, even tho I know better. Heh, I do it every time!
Add new impeller, and gaskets to your list.
If you can't find the assistance you need here, try the folks at AOMCI.

Ok so I purchased new lower unit seals and spark plugs online today. I also ordered a new impeller. Anyone have info on easiest way to clean carb or link to a good resource for education?

Good advice about the FACTORY manual. Hunt around until you find one.

These motors are a little weird to work on. Lower unit seals take special tools. If it has milky oil or obvious water, then start work on the seals. Otherwise just service the water pump.

The carb is a funny thing too. Be very careful with the idle mixture screw. Read the whole fuel system section of the manual first to get familiar.

If you have no spark at 1 or 2 cylinders, it could be old coils. Age cracks them, all of them sooner or later. Then they just arc to ground instead of firing the plug.

Pull the flywheel and check the ignition system. A little corrosion on the points will shut off a cylinder too. Use the factory type puller, only.

I found a cherry 9.5hp in perfect shape. Got all done with ignition service, fuel system service, and lower unit service; all just to find out it needs a lower crank seal.
Got a little unexpected work ahead of me. I'm seeing that more and more these days.

Old timer told me years ago to change seals. I read it again recently in an old factory manual under tune up procedures. Alcohol makes it worse.

Pulled the lower unit last night and it looks great. The impeller is in perfect shape with no cracks or dry rot. The house is also great with no scoring of any kind. The lower unit oil looked normal and was not milky at all. The spark plugs looked older and those are obviously being replaced. I checked compression and it was 75 on top and 80 on bottom. I didn't think about pulling the top and looking at the ignition but now I will. I already have a manual but don't really like it. It doesn't seem to be easy to follow and isn't very detailed. I will defiantly be looking for another one.

I have a 66 evinrude 9.5. It's identical to your Johnson. I have been through the lower and replaced the seals. New water pump. New gaskets in the carb and the old fuel pump still works. If your motor is firing but not starting, check the angle of the float arm in the carb. It has to be adjusted or the pin will not let fuel into the bowl. Read the manual and then check this website https://www.leeroysramblings.com/OMC_9.5.htm.
Good old Leroy well tell you more about about that little motor than you want to know. It's a great motor and will push a small boat well. If you got any questions shoot me a pm. I may not know the answers but might be able to help some.
Oh by the way, check your local auto parts store for a role of gasket material. You can cut your own gaskets a heck of a lot cheaper than buying them.