Its hard to say what the problem is, but if your kr8 cartos are working, albeit clogged, directly on the 901 batt, then there is an issue with the adapter. Make sure all contacts are very clean (paper towel with alcohol will remove char, if present, which can break the contact). In general, not all kr8 cartos are compatible with 901 batts. Yours are, but the adapter itself might not be for you cartos or batt, even if it screws in fine. Subtle differences in centerpost length between models has made this conversion less than straight forward.
I would not recommend drilling out the carto. There would be less risk to the coil by using a long safety pin, which you carefully push up through the batt-end center hole, and carefully make sure it comes out the filler center hole, then sort of wiggle it around to try to get the hole larger. This is one way that there could be a clog. This is the case if you pull air through the carto while not attached to anything and it is sluggish. If it is a good easy draw while not attached, then it is likely that the air is getting blocked due to the connection to the 901. I have a DSE905 screwdriver, which uses a 901 atty, but airflow is completely blocked with a kr8 carto. The airhole for the 901 atty is on the side of the tube, not at the connection like a 510 atty, so there may not be any way for air to get into the kr8 directly attached to the 901 batt, even if the connection powers the coil.
So if the adapter works with one cartos on the auto, and none on the manual, it is likely the adapter is just off in specs enough that differences in connector dimensions between the auto and the manual, and yes between cartos, is enough to make it work in one situation and not the other. Its unfortunate, but as I said, the 901-to-kr8 conversion does not have a great track record in general.
Solution to me would be to simplify your life and either get a KR8 kit, so you have a couple batts and a charger, or go in the direction of 901 batt with 510 cartos with the appropriate adapter. I have read much less issues about 510 adapters and this conversion than 901 to kr8. Especially in the beginning with
vaping, I think its best to have a simpler system that has a better history of working. Kr8 batts will be a bit more voltage than the 901, too, and thus a stronger vape with the same cartos.
Good luck!
