Auto trans fluid 2

I was disappointed to find out there is no dipstick to check your auto trans fluid. The shop manual is not much help, you need some kind of Jaguar diagnostic reader and a special tool, and they want you to discard the inspection plug and install a new one when you are done. And the fluid has to be at a certain temperature.
So, I called the dealer for the first time and they gave me the first available appointment middle of next week.
Question: Has anyone had any luck with a neighborhood mechanic checking the auto trans fluid?
My trans has a quirk in 5th gear only, and I just want to see if there is the correct level of trans fluid in there.
Thanks,
P.