I've just completed my 50 hour maintenance routine myself. I noticed splines on the the main shaft running from the engine to the transmission are not well engaged. I havent been able to get an accurate measurement of spline engagement however I roughly measured it with a piece of wire and its between 3/8" and 1/2" of engagement between the transmission input spline and the mating spline of the universal joint casting.
I've reported it to my Dealer. They checked with JD and there are no recalls however the dealer locally reported other 1026R's on the lot being similar in appearance. Take a look at your own tractors. We may have a first model year problem and maybe there is no problem at all. What do the 2305's/2320's etc. look like? Is this a common issue? I hate it when a dealer tells me "Yeah, they're all like that!!"
Why do I consider this to be an issue? Well for starters to replace this splined driveshaft joint involves removing the transmission from the frame or removing the engine to get enough clearance to remove/replace the drive shaft. When the spline wears, (it will if there is only marginal spline engagement) combined with universal joint wear, which will accelerate spline wear, there could be a situation where the warranty is over and the repair bill could be hefty, particularly if the input shaft to the transmission is damaged.
Check yours and post your findings.