1) Same issue here with hot spots, mine are small, but black and burnt, as soon as I taste that, I stir, or eject. I don’t have an answer, I’ve read a bunch of ModPod threads on Reddit, a lot of posters there had uneven herb, and shelved their units. I don’t want to give up yet. As I posted (3) above your post, putting the load inside the joint, held in by cup screen reduces if not eliminates it. I’ve gone to a medium grind, dump in two scoops, as you can double or more the capacity over just loading the screen cup, and nothing can fall into heater. If your mouthpiece does not have an inner screen installed, just add one, the NUB has one already. I’m still using the flat SS Clapton’s that came with it, but I believe he’s changed the default coils more then once. These dual SS coils read at 28ohms, and so far I’m using a TCR of .00265.
2) So far, I’ve given up on capsules, tried my Mighty S&B ones, too much extra heat required, hot air gets around the capsules, etc., other user options meant buying from other sites and testing etc. Loading the mouthpiece “joint”, is like having a larger capacity cup screen. After a few hits, pull it out and shake up the medium grind load.
3) SEE my #1 response.
4) So far I’ve been conservative on heat, but my ABV is definitely lighter then most of my other devices. I’m going to go higher to test.
Remember, you have to find the balance between your draw SPEED, and draw TIME, as well as the AIRFLOW setting on the Stempod, and of course your heat setting. Though none of my attempts have solved the hot spotting when I try the cup screens. That’s why many find a Stempod “finicky”, lots of variables. Seems a lot of folks give up on temperature control and go back to wattage, but that is when you really have to feather your heating, or you can over heat and combust.
Good luck.