Need to replace top volume control
Grace Mondo internet radio has developed intermittent function in the top volume control knob. I am guessing the shaft encoder has failed. Twisting the knob will randomly raise and lower the volume, regardless of direction of rotation.
I don't know your radio so I don't know if the volume control would be a rotary encoder type (usually identified by just a number stamped on it) or a potentiometer, usually identified by a number with either a k or k Ohms after the number denoting x thousands of Ohms resistance stamped on it).
If it is a rotary encoder try cleaning it and see if that resolves the problem.
Here is a link to a video that shows in principle, what to do.
Here is a link to the ifixit Grace Digital Mondo Repair guide which may be of some help to gain access to the encoder.
If it is a faulty potentiometer (or even an encoder that has failed mechanically) hopefully there will be information stamped on the case of the component which will help if you have to order a replacement part, as I cannot find a service manual for the radio online from which to get the part information.
Hopefully this is of some help."
Try replacing with an Arduino rotary encoder board from Ebay or Amazon. Might work.