Leaf problem (lots of pics)

I wouldnt worry to much about flushing and adding un needed stress to the plants. Just straight water for 2 or 3 waterings then back to feeding. Just feed a little less when you resume nutes.

Let's not forget though guys, as I wrote in my first post, these 3 white widow autos are nearing the end... I have only about 10 more days... Maybe I should just keep flushing till the end?

Any thoughts?

you should get the excess fert out because if you don't, it remains in the plant when you consume it. this isn't so good.

1300-1400 ppm range, while staying around the 5.5-5.7 PH, could it be a lockout?

I think that is a little low runoff for ph and ppm are pretty high (depending on .7 or .5 scale). What is the ph of the water you are putting into the soil vs the runoff? That will give you an idea of how 'hot' your soil is. If it were me, I would be using 6.5ish ph water going in. Some ppl I know use 7.0 water and the plants love it. I believe it's low ph and they are having a hard time taking up P Ca K ang Mg.