First my MTD LT-17 lost 6'th gear and wouldn't go up inclines in 6'th. A few weeks later it lost 5'th gear and now it won't go up an incline in any gear. It goes reasonably well on the flat though. I took the mowing platform off and took a look at how it changes gears but I couldn't figure it out. Can you explain how the different gears work? Thank you.