Hello dtm39,
If your left AirPods has no sound at times, there are some steps that may help resolve the issue in the Apple Support article, If your left or right AirPod isn't working.
If there's no sound in one AirPod
1. Make sure that your charging case is fully charged.
2. Place both AirPods in your charging case and let them charge for 30 seconds.
3. Open the charging case near your iPhone or iPad.

4. Check the charge status on your iPhone or iPad to make sure that each AirPod is charging
.

5. Put both AirPods in your ears.
6. Play audio to test both AirPods.
7. If an AirPod still isn't working, reset your AirPods or contact Apple Support.
If you're still experiencing issues after working through these steps, a few additional details may help other Apple Support Communities users assist you.
• What do you mean when you say the AirPod isn't fitting? Does it fall out of your left ear?
If so, Choose your AirPods Pro ear tips and use the Ear Tip Fit Test is a great article to reference to ensure you have the best fit.
All Our Best.