I have a toro belt drive walk behind mower that started acting up on me today when I was out mowing. I am having a lot of trouble shifting the gears and cant even put it in 5th and really hard to put in reverse. The gears seem like they are stuck. Is there any grease or oil I should be putting inside the transmission? I greased up the coupling on the outside about 2 weeks ago. Do you guys think my trans is about to go on it?? The mower is about 3 years old. Any input is great.