Wyze robot vacuum charger contacts issue

[lhntx00]

I have two Wyze robot vacs, which I love. I kept getting notices on the downstairs one (Nessie), that she was powering off because the battery was low. I bought a new battery and installed it, even though the one that she already had was just over a year old, but the issue continued. I discovered that I can move her back and forth a bit against the base contacts and she will start charging. The issue continued happening, so I switched out the charger base and power supply with my upstairs vac (Sasquatch). Now Nessie is charging fine, but Sasquatch is having the low battery issue. As I mentioned, I can move the vac side to side on the contacts until a sweet spot is hit and the vac will start charging again. I have cleaned the contacts on the charger, and the vacs, but I’m still having to manually manipulate the vac to the charger contacts every day. So the question is, how do I figure out what is the issue? Is it the power supply? Is it the charger base? Since I can move the vac against the contacts to make the charging start, I’m thinking it’s most likely the base, I just don’t see what could possible be in the base that could stop working correctly.