I almost always have these issues at higher magnifications with both of my BTs. My Lunt 100 45 degree ED is especially sensitive to eyepieces with the "safety cuts" in the outside of the tubes. The collets of the focusers do not play well with these. Some brands of eyepieces are better than others. The ES 82 degree 4.7 and 6.7 pairs that I have seem to be the worst. Others such as the Docter 12.5 and Pentax XL14 pairs are O.K. I also have trouble with the Televue Delight 7 pair. The best are the Baader Morpheus pairs, which don't have the cuts, although I do sometimes have to fiddle around with the 4.5 and 6.5 pairs to get them aligned.
I've found that loosening one side up enough to turn it in the focuser will usually get the alignment better, but sometimes I have to try turning both sides, and also make several small turns to find the best combo. Sometimes I can't get the alignment very good with any amount of fiddling. Fortunately my eyes and brain will merge the images when quite misaligned, but it tends to give me a headache, and when I put another eyepiece pair in the instrument, it takes a bit tor me to get re-adjusted to them.
I also have the adjustment tool that the OP mentioned, and have used it to gain some improvement in overall alignment of the Lunt 100. For me, it was not easy, and I could never get it perfect. I would not recommend trying it until you have established a consistent misalignment after fiddling with your eyepiece mounting, and a consistent direction of the misalignment. My objectives were actually "cross-eyed" originally, and still are, but just not so bad following adjustment.
As Tom said above, these eyepieces and the mounts and collets are not exactly precision devices so about all that can be hoped for is to get close enough that a bit of "fiddling" will get you acceptably merged images.
Best of luck!
Edited by oldmanrick, 28 July 2021 - 06:21 PM.