Congrats on new x728. With the 1026r and 60" drive over deck ,did not get auto conn MMM . I had put some light grease on the collar, on the splines of shaft and gear and was still having problem ,oh had the PTO set to the rear.
Finally after 15-30 min of getting madder and madder decided to try something else , sprayed some WD40 on splines ,slides on with no trouble . Have been spraying WD40 now every time ,works first time every time. Light grease so far hasn't helped , maybe with more usage it will get easy, or order the auto connect like I did last week.