No Output From Right Speaker

I'm not getting any sound output from the right speaker.
It works fine on the Linux machine, so nothing wrong with the speaker or connecting cable.

What I have tried;

• ran sound troubleshooting; no problem found
• uninstall all sound devices in device manager and reboot
• checked all sound configuration settings
• restored system image backup from April 3rd with Macrium Reflect recovery media

Don't know what else to try?

Could this be a failure on the motherboard?
Do I have to add a sound card?

ASRock H370M
The BIOS firmware is 3.40 from late 2018.
There have been (3) updates released since then.
They appear to be mostly Intel microcode updates.
For all firmware updates after my current version, ASRock recommends not updating if the computer is working properly.

I think I did a BIOS update after installing the motherboard, but probably not since then.

 

Is there any balance options under the audio settings/card?

 

There should be seperate volume sliders for left & right speakers.

 

From the Sound dialog > selecting Playback > Speakers > Properties > Levels tab
there is an overall Volume setting and a Balance button.

The volume is set to 100% and the balance levels are also 100%

- downloaded the Realtek driver from the ASRock web site and installed that
- there was an Optional Device Driver Update (Realtek) available through Windows Update that I also tried

After numerous device uninstalls, driver updates, etc. and also Windows System image backup restores going back 8 months,
I've tried everything I can find, with no success.

I may try ASRock support through their web site and try to determine if it is a motherboard issue.

I'll be looking for a basic, inexpensive sound card.
Any suggestions?

Thanks.