Figured it might be time to give cleaning my GEMS MAF a shot (168K miles). It was really pretty easy. I didn't elect to drill out the rivets and remove the sensor post from the housing tube because it's pretty accessible in it's assembled position.
Here's the steps as I performed them:
1) Remove MAF sensor housing assembly from the engine air intake (two clips MAF inlet, hose clamp MAF outlet, squeeze the electrical connector (pushing the wire in) and pull off)
2) Gently work/pull with fingers the plastic collar inserted in front of the MAF housing intake screen and remove the screen.
3) Take the housing outside and spray 1/2 a can (at least) into the small tube in the housing.
(Hold the MAF housing slightly down from horizontal to allow the excess cleaner to drain. The air path through the tube exits out two ports on the underside of the "T" shaped sensor tube post. I was careful to not place the cleaner nozzle into the tube so as to avoid possible damaging of the tiny devices in the tube.)
4) Let it dry... 1/2 hour or so...
5) Reinstall the screen and fixing collar into the housing inlet.
6) Reinstall the MAF sensor housing into the engine intake tubing.
Diassembled for cleaning
Sensor cluster before cleaning
Ready for cleaning
After cleaning (note: you can see the color of the devices now)
Close up of cleaned MAF sensor core devices
Things didn't really appear too dirty. I've taken the vehicle for a preliminary drive and haven't yet reset adaptive values. The only thing I've noticed is the transmission is downshifting a little "aggressively", so something has changed...
I'll wait for a couple days till I post a final success note...