Increasing extrusion, adjusting height

There's surprisingly little information available on how to adjust the tension of the extruder idler. Mostly it's just "adjust until appropriate", whatever that means. One page mentioned that there's a long range of acceptable tensions, so I guess I will start with loose enough that it doesn't grip properly, then increase gradually until well after it starts gripping.

But first, I realized from looking at The Calculator that the Z steps/mm was a little off - it should be 2560 but was 2600. Not a huge difference, but might throw the layer height off a smidgeon. So I fixed that, which in turn made the Z offset wrong. So I have to re-calibrate that. 19x10mm first, then to reach the 10.43mm hex bit took another 4x1mm plus 5x0.1, so total 194.4 + 10.43 = 204.8, 3 millimeter higher than before (then - 0.2 to allow for hotend expansion, according to nophead). No wonder that test print curled up on itself.

There was a rumbling sound when homing X+Y, I should probably recheck the fastening of the gears if I see any sign of X or Y slippage.

The result is good, seemed to have slight initial sticking problems, still has a layer or two with gappiness and the top is still not fully closed. I will try slowly increasing amount of extruded material. (Cube #18)

Reducing my fudge factor to 50.0 / 30.0 and increased height to 204.7. Decent print, still with some adhesion problems, but the top looks a little better. (Cube #19)

Reducing to 50/27 and increasing to 204.8. (Cube #20). Adhesion pretty good now, but worth adjusting once more. Also less gap at the top infill.

Trying one more adjust: 50/25, 204.9. Now it's starting to get rising corners and thick layers. Somehow I manage to get overextrusion and underextrusion at the same time:(