Fatburgok, got the p-trap and trap arm off. ran a snake a few feet and cranked. no results.
so i ran it futher down and hit black gold or whatever burned up lard is called. big wad of black goo with some odd bits about 8+ feet down the pipe. the snake bit captures a hunk every time i send it down. either the downstairs neighbor is pouring used lard down the sink or the previous owner of my mom's unit did.
at this point i'm calling it off. no point in me trying to fix the downstairs neighbors issue. anything in the walls is the HOA problem, and if i do any damage it will be my problem. i would need to get roof access to have any real chance of clearing it.
It is HOA problem, but it is some what an easy fix by running a snake to clear the blockage. There is a possibility that there is a burr/broken pipe at fitting where clog occurred.