Troubleshoot tray power indicator in csd

["Mark C. Stafford" <mark.stafford@gmail.com>]

I think have a problem with csd-monitor in cinnamon-settings-daemon
3.8.4-2 (buster).

Lately the battery icon in the tray intermittently stops updating the
screen, leading to no visual feedback prior to low power when I'm not
paying attention.

I've relieved the symptom by running pkill -HUP csd-monitor on a
guess, and the tray icon starts showing accurate info afterward.

acpi has consistently returns good results, and there are no errors
under /var/log mentioning csd-monitor.

How can I debug, or collect more useful feedback about the problem?

TIA