Trying to contribute to this thread since it has been so helpful to me. 2002 LX470, 248k miles. Front driver and rear passenger locks did not like to fully actuate using remote or tailgate keyhole mechanism. This behavior only exhibited in hot weather. Right now they actually work fine. But I took the opportunity to work on it now--I have better patience for this sort of thing when it's cool out and no bugs.
Reading the thread, I honestly wanted to replace my whole mechanism. Yes, the motor is the issue, but my logic is that buying an authentic Aisin assembly lasted 15 years (symptoms started back in 2017) so it should last another...15? 10? Even if it only lasts another 5 that would be great. Bit the bullet and got DS Front assembly for $126 and PS Rear for $90. Time is money and I'm ok with that price.
Everything with the install went just fine except a little bit of the yellow clip for the PS Rear was brittle and snapped off. Enough material was there for me to just use a tiny zip tie to hold the clip against the rod. It was the "cam", or "curvy part with the bump" that hugs the rod which broke.
For the DS Front, definitely absolutely recommend removing the handle as it provided the necessary access to the pink clip that connects to the lock cylinder. I don't think I could have done it otherwise. Access to the rearward two screws is achieved once the handle rod is disconnected (not the cadmium plated lock cylinder rod). Access to the forward screw is trivial. Removing the handle also allows access to view and or manipulate the two snap in plugs on the annoying white plastic guide plate. Or verifying the window guide track has been reinstalled correctly...etc etc. Just do it!
After accomplishing the DS Front, the PS Rear seemed so easy. There is only one metal arm, no lock cylinder, no annoying white plastic guide plate (integral tube instead), and the whole assembly can be removed from a big cutout just to the left. 2.5hrs versus 50 minutes for this first timer.
I recommend checking actuation and closing/opening doors before resealing the plastic and buttoning up the door. Oh and that reminds me, I used a utility knife to cut through the thick tar like sealant. Gently pulling the plastic and cutting through the tar made it quick, avoided tearing the plastic, and allowed for some tar to be on both surfaces for resealing. I suspect my winter conditions allowed for this cutting... maybe it's just plain goopy when hot out.
If you have the cash, I highly recommend remove and replace.