Stipping and Random Results Need Help please

[Nearly-There]

I feel like I'm banging my head against a brick wall at the moment. I am trying different parts and getting random results. When I think I have it right with a part something throws a spanner in the works.
I run 3 of the same item (call them part A, these are 6 series ali); dye two of the items different colours then 1 clear. The clear worked so did one colour but one colour had an issue. Everything appeared ok at each step I put a meter on the parts before they went into the dye to check they had anodized, all had. Take the items out of sealer, spray as I lift them out to keep wet and straight into clean distilled water. I gently wash over with my hand whilst in the water. Lift them out and wipe over with WD40. One colour looked streaky (it didn't look like this coming out of the dye). Wipe with copious quantities of WD which makes it look better for a few seconds. Eventually the dye goes translucent in patches and not all over. I strip this, re polish and clean then De-Smutt.

Two days ago I anodise a part and dye it no problem (part B) 7 series.

Today I run 2 part B and the part A above.
Part A- all appeared ok coming from ano and dye, I decided to leave it in the sealer longer (for 30 mins instead of 18 mins), this helped alot. No streaks no rubbing off but still not 100% but it is passable.

Part B- One 6 series and one 7 series ali. 6 series clear anodized turns out a little cloudy with a brown patch on one side almost like faint wood stain in pattern and colour) I am assuming this is something to do with in ground polish or maybe tiny scratches from the linisher which have been exaggerated. This will need to be stripped, but am a little worried because of below.
Part B 7 series - Again, no apparent issues coming out of the ano or dye (Blue). Take it out the sealer and large streaks are all over the face of the part, they look as if something has dribbled down the face. I think maybe something was not washed off (although I am very careful with each stage). So I strip it in Sodium Hydroxide it turns black. I mean solid black as if it’s been anodised that colour. I wipe it some of the black comes off but leaves a lot of black/green deposit on the surface. I run a meter across and get a reading so the anodize off. I go in the tank again instantly black. I thought I’d make up some fresh stripper, same thing happened black again. I cannot get the part to strip back to bare ali.


Info- My lead plates have gone very dark, if I scratch them they go shiny again is this a problem, if it is why does this happen? My ano tank has particles of black in it, some fine which sit on the bottom others which float. I have only run approx 8 parts through it since changing the solution.
I am meticulous with my pre cleaning, I use a solution to remove the polish then wash this off. The part is then washed in detergent then rinsed again.
My sealer is green and clear. However, it was topped up recently. The ratio was triple checked before adding. I have noticed something dark sitting on the bottom of the tank maybe granules of some kind or the dye but the rest is still clear.

I really need help in figuring out what is going on, the guys I am supposed to be doing this for are giving me parts to practice on but because these are actual parts I can’t just throw them away, I do have to strip and re-polish.

Many thanks in advance