Zolo z2000

I’ve had these bad boys for like 2years. I got them back in 2017 couple days after they came out.
I have no reason to upgrade to any newer ones cause these are amazing IMO. Few months ago I saw they got their price cut in half, and that’s fine imo these feel like premium quality wireless headphones it does the exact same thing as any newer headsets.

Beside the scratches, and normal wear of the case my headset still look flawless except for the left
earbud that won’t work properly, the buttons work except the audio, i don’t hear anything sometimes. I have to put them both back in my case for a second and wait for them to connect to my device again, and wait to see if that worked. Most of the times that does the trick but other times i have to do it like 2 or 3 times.

Is there anything i can do to fix this? maybe buy a replacement case or replace the left earbud?
I don’t want to loose them tbh, these are my very first wireless earbuds i’ve ever bought with my
own money. So there like important

Look inside box and buds, with a bright torch to see if any dirt?

Also, using a tech wipe, give the terminals a clean, and a blast of air… A quick service as it were!