i've never seen the acess hole. but here is a trick. if the hole is directly above where the nut needs to go. get a short socket. you might have you use 2 nuts. but cover the nuts with wheel bearing grease, and then stick them in the socket. the grease will hold them in there. then put the socket on an extention and snake in down the hole and there you go. you migh thave to use 2 nuts so the nut is flush with the tip of the socket so it doesn't sink inside.
I use the trick all the time on my toyota... they love to do stuff like that.
and i use wheel bearing grease to hold the large O ring in place when changing my oil. it works great for holding things.

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