Problem with remote not being able to controll volume reliability.【NAD T758 V3i】

All of a sudden now, my remote can only turn volume up or down in increments.

Before I could be at say, Volume: -10dB ..

Hold the volume up button and raise it smoothly to say, Volume: -5dB ..

Now when I do it. At -10, holding up, it goes to say -8, and thej stops. And I have repeatedly tap the up button to get to -5 ...

I have the original remote, google TV remote calibrated for NAD T758, and logitech elite with the companion remote.. So can't be a remote issue, they all produce the same result. Even when I hold the remotes directly infront of the newly cleaned window on the NAD directly infront of where the ir-sensor is..

What can I do to fix this?