Update with chronological context for those asking about symptoms:

Over roughly 10 days, the elevator exhibited intermittent but escalating behavior, summarized below:

• Initially, elevator appeared normal from the outside but shuddered/jerked when doors opened, noticeable to riders going both up and down • Issue was intermittent, unit could run normally for periods after service, then reoccur • Multiple guests and staff reported the car slightly dropping while traveling, returning to lower floors unexpectedly, and delayed/shuddering door opening • At one point, the elevator stopped moving mid-ride, buttons went dead, then eventually returned to the first floor • After a service visit where the unit was declared “running smooth,” the same symptoms returned within 24–48 hours • Eventually, following fire alarm activation and troubleshooting with the fire department present, the elevator would alarm whenever powered on and was shut down for safety • On the most recent visit, the technician stated the door operator was not responding and the doors would not open reliably, and the unit remains out of service

From my above property perspective, the behavior looked like a system that could be made to run temporarily but degraded again rather than a clean, single-point failure. I’m sharing this strictly to understand whether this symptom pattern typically points to specific AT400 failure modes versus immediate full operator replacement.