Rob Hickman at AFS said that I could reset the capacity on the left tank, by downloading latest software for 3500 and pushing select knob to reset capacity. This should clear the left bar not displaying on the 3500 per Rob.
Downloaded v 8.6.22 and installed on 3500. Just installing it clear the capacity field on tank 1 to "0". Reset capacity to 52 and all appears to be good.
Thought I had the latest s/w laoded but guess not. 4500 was already on v 8.6.22.
