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.
Had the same problem. Grace contacted me and said they could find a problem. When I receive it and if the problem occurs I will video tape and send it back. Cost me 35.00 to send it to them.
由 detectorist 完成的
Well guys, I ended up just living with the crippled control, and not it is December 2020 and the Receiva aggregator site is going down, so I expect these Grace Mondos to turn into doorstops.
I really enjoy the table-top form factor for internet radio, so I just bought a new Grace Mondo Elite which supposedly has a chipset under the control of Grace and should be good for a few more years :)
由 jerome whelan 完成的
I went to https://myradios.gracedigital.com/ and entered the serial numbers of my 2 old Grace radios and now I can still add stations to the "mystuff" folder. So they are not totally dead yet. I also got XM Radio to send me a code for a free Alexa Dot since their service no longer works on the old Grace radios.
由 Richard Smith 完成的