Honestly speaking I am not a technical expert. But what I can figure out is, if the volume level works properly from the remote but not with the volume knob, then you can assume that the major part of the avr is fine barring the volume pot.
If the volume level goes haywire with both, the remote and the knob then there may be a bigger issue.
I am sure other experts may be able to tell you more precisely.
Regards,
Nitin