I have a bolens 17 hp riding mower. Last year it seemed that it didn't want to move in the lower gears but would move OK if it were in gears above 3. the first time I started it this year I put it in gear and it moved out of the garage and then wouldn't move anymore. I'm just not sure how to troubleshoot the trans on this. Any help?

At first I though the transmission teeth are worn off or cleaned off in certain gears on the input/output gears. This happens when you "dump the clutch" when taking off, or changing gears without completely clutching.

Now it not moving could be the input shaft and/or bearings are worn. When this happens the input pinion is not properly aligned with the mating bevel gear, causing the input motion not to be transferred to the other gears. Causes can be normal wear or excessive tension on the belt.