This derailleur was incredibly stuck before I took it apart and the only joint that’s giving me trouble is on the underside of the parallelogram.

Has anyone here ever taken one apart? I’d like to know if the grey metal piece that actuates the guide can be removed from the main plate. There’s a similar grey metal piece inside of the parallelogram that could be removed but I’m trying to figure out how to pull this piece off.

I’ve tried WD40 and PB blaster. Curious to hear if anyone else has taken one of these apart and has a tip for me.

I've never taken one apart, so can't offer any advice. If it were me, I'd be inclined to try a small amount of "percussive maintenance" to coax things apart.

I do appreciate seeing one of these (mostly) disassembled! I've got one in the parts bin, purchased out of curiosity. I'd wondered how the internals worked, and didn't consider that it might be a simple linkage rod that kept things parallel. That seems like it would be prone to wear,

Steve in Peoria

I've heard they're a horror show of unnecessary complications. Still, pretty cool though...

My "complicated" RDs end with LeTechs.

I don't think that piece is removable. See

https://pardo.net/bike/pic/fail-059/000.html

FWIW: the link is non-secure HTTP (e.g., "http" vice "https"); this forum's software appears to convert all links in posts here to the secure version. For the "pardo.net" site, the secure version doesn't work on all browsers. If it doesn't for yours, simply edit the link to remove the letter "s" in "https" and it should work.

See link above. In addition to the relatively thin - and thus not terribly strong - wire serving as one of the parallelogram plates (reportedly about 1mm in diameter), the Superb Tech also supposedly had issues with pivot wear and their internal springs. Plus, per the above link some versions also used the same sprung pulley design as did the MounTech, with all its issues.

The SunTour "Tech" derailleurs were also apparently a royal pain to reassemble once disassembled.

Neither the late Frank Berto or Mike Sweatman (who runs the Disraeli Gears site) had/have much good to say about the Superb Tech's design.

Somethings are better left alone

Gunsmiths make lots of money from guns brought into the shop in abox or bag. Ain't no bike shop employee outside of one or two in Pakistan or Sri Lanka knows how to put that back together

Just a note about taking derailers fully apart, it's better not to turn the limit screws any more than necessary, lest any plastic thread-lock pieces get worn away by the threads.
The plastic is old and likely shrunken already!

I also agree with the others that this derailer's design doesn't appear to emphasize long-term durability.
Used gently, in a clean environment, it's likely going to be fine, but dirt/water and/or hard use is going to invite trouble.
Bumpy roads may fracture the fragile A/B pivot springs, dirt/water will eat up the pulley bushing and pivot surfaces, and hard shifting may break the locator link rod.