Hi
grostonAs before I've marked up comments in red in your post above until I reached one step which looked wrong and the next step which didn't make sense to me.
Please try again including
Ed's suggested 45s which give two immediate placements.
Thanks
Ed for that compliment, a practice inherited from a former regular on this forum.
Continuing later, with mental arithmetic, from the step reached above, I think the solution is
So neither of 1,2 in r1c6, they must be elsewhere in r1 and n2.
Cheers,
Andrew