Problem with case contact surface

I am having issues with my earbuds. Occassionally they will stay connected to bluetooth when I place them in the case and close it. Other times they won't wake up when being removed from the case. They will charge, and often it is when I am charging the device that I have the best chance in waking the earbuds...

I think I sometimes hear an electical arc sound when fiddling with them in the case as well.

I have standard earbud tips on that came with the earbuds, they are fully installed on the buds (not sticking out or precenting them from fitting in the case), the buds are not floating in the case, I have cleaned the contact surfaces and rubbed them with some 91% isopropyl alcohol, visibly they look clean as do the contacts on the buds, I opened the case and the components don't look burned (but I don't know what else I'd look for). The audio quality is fine... when they work they are great earbuds. I got them specifically because my last $200 of Sennheiser buds had the batteries die and the replacement was tricky... so I was really hoping I'd be able to repair my new buds.