210 variator adjustment bolt slipping?

Hi all,

New to the forum and new to the John Deere community with a 1980 210. The tractor is in good shape, but I have been going through it to make sure there aren't any loose nuts or screws and that the belts are adjusted appropriately. I adjusted the variator based on the instructions in the service manual and all seems fine. The tractor moves through the gears and with the variator in the first (slowest) notch. However, I noticed that the bolt that is used for the variator adjustment seemed to slip upward after running the tractor. I am pushing the bolt down as directed, so the bolt is tightened in the lowest possible position after the adjustment. I am wondering if this is normal. If this is not normal, what is the torque spec for this bolt? I haven't been able to find any information about how tight to go with that bolt. I feel that I am tightening it down pretty good but am not using a torque wrench.