I bought a HD ZT 60 with 105 hrs. First ZT. Read the owners manual. Found the levers which engages the transaxles. Didn't matter if it was pushed in or pulled out, always engaged. And he hadn't replaced the oil and filters either so I drained and refilled/replaced engine oil & trans. oil, hoping that might make a difference. Nope. I can pull the levers out and still have power to the wheels. No unusual noises. Just as if I had never pulled them out. Ever heard of something like this?