Owing to my laziness, it took several weeks for me to fix a patio power issue that had stopped my feed. After restoring electrical connectivity, I upgraded to Stretch using the steps outlined at RaspberryPi.org. I updated PiAware manually using the steps at the corresponding site. Now there is no data feed any more.
Here is the piaware-status output:
PiAware master process (piaware) is running with pid 507. PiAware ADS-B client (faup1090) is _not_ running. PiAware mlat client (fa-mlat-client) is _not_ running. Local ADS-B receiver (dump1090) is _not_ running. _no_ program appears to be listening for connections on port 30005. faup1090 is _NOT_ connected to the ADS-B receiver. piaware is connected to FlightAware. got 'couldn't open socket: connection refused' dump1090 is NOT producing data on localhost:30005. Your feeder ID is v-w-x-y-z (from /var/cache/piaware/feeder_id)
How can I get back online again, please?