So, I've got this Deere GT245 I bought new in 2005, 54" deck, 125 hours on it. Tried to cut the lawn today, and right from the get-go the blades were hesitant to engage, and it APPEARED that the left blade was spinning slower than the right. Both would only spin for maybe 10 seconds before disengaging as if I had gotten out of the seat. They would reengage normally, but only run another 10 seconds or so before disengaging again. I've never seen this before... can anyone give me a clue where to start troubleshooting?