Help needed on Trim settings

[AIR-TASTIC]

Q3. What else should I do?

step 1 tune the bar.

remove bar from kite, and tie the ends with some lark's head to a strong pole. stretch out the lines and set the trim at maximum power, pull the bar all the way in.

All 4 lines should be exactly equal tension, both rear and both center lines should be exactly the same.

If the rear lines are too short you can pull hard on the bar and stretch them out a bit. Or you can adjust the knots on the bar.

Once you have the bar tuned, go back out and see how the kite behaves and at this point we can start talk about setting the trim. But don't do anything until you have first properly tuned the bar and made sure the lines are exactly equal.

I believe on a fuse the 5th line is slack so that doesn't have to be tuned.

OK

Just for the sake of ticking every box, I have re-measured the 4 lines. All are of same tension, give or take 0.5cm, I assume this tolerance is acceptable as to be =.
This was done with the trim adjuster full out, ie at full length, not pulled down at all, and the bar pulled back as much as possible
When you say "trim at max power", are you meaning MAX IN or MAX OUT?? With it MAX IN, the lines are nowhere near close to being equal, even though these lines are brand new. Ditto my old lines, which I gave up on, thinking they were the problem
So if it is MAX OUT, then they are all equal, and I should fly my kite more like this than with the trim adjuster more or less fully down?

[edt]

Just for the sake of ticking every box, I have re-measured the 4 lines. All are of same tension, give or take 0.5cm, I assume this tolerance is acceptable as to be =.
This was done with the trim adjuster full out, ie at full length, not pulled down at all, and the bar pulled back as much as possible

This is exactly right. Pull the trim all the way out, bar pulled all the way back. Kites are tuned so that when you have the bar like this the kite will be slightly oversheeted

Now pull the trim in about 2 inches or so and ride. If the kite performs well then you are good. If the kite still has problems like flaring or stalling then something else is wrong.

Just trying to keep the diagnostics here as simple as possible right now to see what the problem is.