Can't get 8hp yamaha to shift

So my father in law just gave me his old kicker, it hasnt been started in 5 years. Now i think it is a 2006 as far as i can tell these are the serial numbers i can find on it 8mshu 6g1 s0 058358 x. I took it in the shop and took the cover off, the spark plugs were corroted so i took them out and cleaned them up and put them back in. I pumped some mixed gas into it (new stuff not five year old gas) and it started up after only 5 pulls, runs great. However i cant get it to go into forward or reverse it sems stuck, i didnt want to force it too much and break something. This motor has only been used a couple of times and is in great condition, it was used in salt water. Any ideas would be greatly appreciated!

Thanks

Re: Can't get 8hp yamaha to shift

First disconnect the shift linkage from the top to the lower unit. This should be about halfway down and you'll need a 10mm spanner.

Now try to shift to determine if the problem is in the lower or top unit.

Btw check the lower unit oil as well, if it is pure water or gray oil