Hello all. I have a JD STX-38 with yellow deck. Last week, near the end of my mow job, the spring lever on the top of the deck (the lever that engages the belts to the blades) kept popping loose. After some investigating, I found one of the pulley assemblies that mounts the blades had come loose from the deck. I tightened that back up and thought the problem was solved, as this week, the deck sounded tighter and less noisy. It also worked fine though most of the mowing. Near the end, once again, the lever started popping loose. All I had to do to fix it was shut down, and reach down there and move the lever back over. I can see the lever from on top through a slot in the gear shift lever assembly, and as I continued to mow, I could see the lever working its way loose again. I don't feel any unusual vibrations. I wondered if this might be a common problem with this model and if, being common, maybe there's a common cause? Thanks.