i tested salt it was 2600, watermaid says unit needs 3000 minimum so seems that is the issue with it not holding the 75% output and lights flickering down to 50 or less output, i put salt in and hopefully its all good now, last time i tested was about 4 weeks or more ago and i got 3200, i just assumed it would last longer and if i needed more salt the low salt light would come on, but watermaid said they were getting complaints that the low salt warning was coming on too early so they reset it to not come on as soon, but i would think 2600 is soon enough, anyway hopefully issue is sorted now.... i learnt more todayThat all sounds odd: both your description of what's going on, and their explanation for it. Sounds defective to me, but I know nothing about that brand.
Mine has similar lights for output percentage, but they don't change during normal operation. They are always on, to whatever setting I've set. They represent the settings and so I would not expect them to change at all, unless I change the setting. I also have a "Cell" light that tells me when the SWG is actually producing chlorine. When in standby mode, the Cell light is off. I also have low salt and low temp indicators.
If your percentage lights indicate something other than the percentage setting, then that should be explained in the manual. Otherwise, it's fair to assume something is wrong with the unit.