I just had the same wrestling match with my BW12 mower. What a PITA! I spent about an hour doing all the universal joints (a job that should have taken 5 minutes) and, on that machine, there are 6-8 (IIRC) of those shaft covers that to release. I've never had an implement that had shielding like that before, and I spent at least the first 30 minutes looking at it thinking "this can't be right, I must be missing something". No.. I'm not, I really do need to get some tools out to get at the u-joints to grease them. That aftermarket guard looks nice, wonder why they don't come from the factor that way?!?
I might remove my guards entirely. On some (small) number of machines, I do think the guards make sense. The best example is the wood chipper, your walking around near the shaft all the time and working outside the tractor 100% of the time the shaft is spinning. But on something like my BW12?? I mean, if I'm standing where the shaft could catch me (on the mower or between the mower and the tractor) while the PTO is running well.. I think I've got bigger problems than the rotating shaft! Why on earth would you be standing there while the machine is running?! In fact, why would you run the PTO at all off the tractor using something like bush hog (or frankly, most other PTO implements)? Seems like safety has taken a front row seat ahead of "logical dangers" associated with various implements.