Encoder goes against direction of rotation on TE+IKEA Frekvens Speaker

Hi, everyone–

I’ve got one of the TE+IKEA Frekvens speakers. It’s got a single large encoder knob for volume control. Over time, it’s started to increase the volume while I’m turning the knob to decrease the volume, and it does so per notch of the encoder.

I figure the encoder is failing. Does anyone have any tips on how to deal with this? Is cleaning the encoder a fix? If so, what do I clean it with?

I’ve replaced scrollwheel encoders in gaming mice before (desoldering/soldering). It’s not fun and I wouldn’t want to do it except as a last resort here. Figuring out the exact or better replacement part will probably be difficult due to a dearth of markings on encoders in general.

Any help is appreciated!