I finally got sound to work reliably. Here is what did NOT work:
- “touch .asoundrc” in the home directory
- remove and reinstall non-free flash and the installer
- ensuring the PCM channel was unmuted and not turned down
I did have to make sure that the correct sound card was selected (I have two). This made a difference for system-wide purposes, but as far as flash went, sites like YouTube were mute.
I finally found a site that gave instructions to install a pulse audio management tool – padevchooser. I don’t remember which site, because I must have trolled dozens, but this solution worked every time (I had to do this once for each user, as each user).
Opening a terminal and running padevchooser opened up the app in the system tray. Left clicking it brought up the context menu. Selecting Volume Control, and the Output Devices tab, I was able to ensure that the correct card was the default. On the Playback tab, I was able to move the stream to the correct card. For some reason, they all seemed to default on the other unused card, which is integrated into the motherboard.
Once I did these things, Flash audio was just fine.