To help maintain the portal, I wired it up so that "read working" would trigger the insertion of fuel to sustain it. Unfortunately the activation of the portal did not preserve its circuit network connections, and so the fuel inserter no longer received the signal to insert fuel, and you can guess what happened after. Worse, the combinator monitoring it is behind the portal's large selection box so I can't reconnect it without deconstructing the portal.
But hey, at least the portal warmup I designed worked first try!