My club has a Maestro V1.11.12 with a 6500. The waterfall will turn from blue to black for about 5 seconds or so, then return to normal. There seems to be no pattern to when it will turn black or for how long. It could be a fraction of a second or it could be for 5 seconds. While it is black, I can see some stronger signals on the waterfall, as if the gain of the waterfall suddenly changed and then changed back. Any ideas on what could be causing this and what I can change to stop it?