Mettler JL602GE Adjustment

Hey all, I’ve been searching up and down for a way to do an external cal on the above mentioned Mettler Balance (JL602GE). There’s actually a CAL button right on the thing.. however, it says ADJ.OFF , where I want it to say ADJ.EXT. I’ve read some things that say certain models are permanently locked from manufacturer. Would anyone know if there’s any truth to that? Additionally, I couldn’t f in d a factory reset button and I tried all the usual suspects (holding all types of different keys while it’s powering on). Does anyone know a secret handshake? I have also inspected the unit thoroughly and found no physical locking mechanisms, switches, or buttons.. it’s a shame because they are great scales (repeatability, eccentricity, etc) but the linearity is shot without the ability to tell the scale what’s what.. ALSO ALSO the internal adjustment button does nothing.. any help is appreciated, thanks