I’m using a NewVape Fine Grinder, I fill to around the air inlets in the bowl (or lower) and then apply a little extra pressure on top of the weight of the battery door to tamp it down, trying to only press once or twice in the same spot. It stays in place unless I shake it hard, but it’s not super tight.
I have had bowls that were pretty dark around the edges and light in the middle, and I think part of that was bad grind consistency and/or packing, but I think how you use the button may also make a real difference.
Here’s an example of a couple of draws as I time things:
Draw 1 (from cold, battery semi-low):
1. Press and hold button.
2. Count until at-temp vibration (8 in this example).
3. Count the same number (8) at the same speed without drawing.
4. Count the same number (8) again while drawing at a low-medium speed with the button still held.
5. Let go of the button and draw for twice as long (16). Reset buzz should come while drawing.
Draw 2:
Identical except:
2. If you reheat soon after the first draw, use the count from draw 1 (8), or at least ~1.5x the new count because it will usually be a lot shorter (maybe 6?).
4. The draw speed can be a little faster but I tend to stay in the medium range.
5. Continue drawing after letting go of the button for 2-3x as long as the count you’re using (16-24 in this example). This should give you a medium-large draw and avoid too much post-draw flower cooking.