Hi S.R.
Welcome to the forum. Flat feed rollers and hard platens do not help when it comes to keeping the type straight on the paper. Feed roller tension (or lack thereof) against the platen can cause the paper to not track true. I have also seen the rubber sleeve of the platen come loose on its wooden core which tends to make things go a little wonky.
The other issue that I have seen on these vintage Remingtons is the line index detent roller can sometimes develop flat spots, lose spring tension or be all together missing. When you advance the paper by turning the right platen knob, you should feel a positive click with each line advanced as the detent roller engages into each notch on the ratchet wheel. Hope this gives you a few ideas of places to look for possible problems. All the best,
Sky
We humans go through many computers in our lives, but in their lives, typewriters go through many of us.
In that way, they’re like violins, like ancestral swords. So I use mine with honor and treat them with respect.
I try to leave them in better condition than I met them. I am not their first user, nor will I be their last.
Frederic S. Durbin. (Typewriter mania and the modern writer)