I was previously running Plex 0.9.5.2 without any issues. But recently I took the upgrade to Plex 0.9.5.3
and within a few days the service stopped responding. Will see if I can dig around to find a log, but restarting the add-on resolved the immediate behavior. Unsure what caused it in the first place though.
From what I can tell, it should be logging into the usual suspects within /var/log. But apart from the installation and start messages I don't see any other complaints from PlexMediaServer there.