I'm no crack mechanic, but calipers aren't very expensive. Since it sounds like yours has some issues, and it's pretty important, I'd consider replacing it. That's just me. Let some folks who know chime in.
I run OME springs and Ironman FCPs; about 1.5" lift. No diff drop or UCAs based on the shop's recommendation. The ride is better than any iteration of 200 I have had. (Stock Land Cruiser, Land Cruiser with BP-51s, LX570)
Over in the 80 section, I think @landtank has a write up on clutch fluid replacement. How to adjust, open, drain, and a discussion on viscosity of replacement fluid.
https://forum.ih8mud.com/threads/blue-fan-clutch-mod-thread-has-gone-to-hell-read-at-your-own-risk.102633/
Mine is doing the same thing. I had it worked on a few weeks ago to find a leak and refill. They never found the leak and had trouble getting it refilled. I haven't gotten into it yet. Mine will run about 30 minutes and then it shuts off and I get the Check A/C message on the MFD. I don't...
You won't. The worst part is lying on the engine to do it. Buy the Ts and hoses and you can pre-assemble them. Spring clamp pliers make it much easier.
It will run dry after about 1L., (maybe it is 2L, I haven't done it in a long time).
The method @2001LC describes is easy and efficient, with minimal mixing of fluids. Run 14 qts through and consider it a 100% change.
My $.02 - I've done the fluid exchange on multiple transmissions: 75k, 195k, 170k via the cooler lines. It's easy (especially if you have a dipstick) and efficient. I didn't drop the pan on any of them.
Find a Toyota/Lexus dealer's site on eBay, you can get the WS for a lot less. If you...
FixAuto Chicago at 4700 W Fullerton. ChiTown 4WD might be able to give you some names, but I don't think they have a rack and they are way out in the burbs.
DIY fluid exchange is pretty easy. I've done it on gearboxes with 75, 175, and 195k miles. All first-timers I think.
This thread will give you info on how you set up the outflow to remove old fluid: Transmission Fluid Exchange Writeup -...