A knob with two finger holes on opposite sides would solve the problem providing balance in every position, but it requires a manufacturing change.
In some older radios it was a piece of felt between front panel and turning knob increasing friction but in the same time it reduced free spinning of the knob.
If the knob is hollow on inside, one could possibly glue a piece of solder wire inside the knob near the dimple and restore the balance this way.
I recall this method used in old Collins turning knobs for increasing the spinning effect.
I have a similar issue. My Maestro main knob has a slight "tight" spot, it doesn't really turn smoothly. It isn't extreme, but noticeable. After the wait for the Maestro I was so happy with it overall, that I didn't report the issue to Flex.. They are small company and it is not like we blessed with an abundance of Ham Radio manufacturing. I kind of hate to bug them with what amounts to a "tactile cosmetic issue".
Keith - AC9S