If they're on that tight, I would just plain not remove them. You don't really have to remove the faceplate to clean and inspect the mechanisms. Vacuuming and compressed air have always done a good enough job on my typewriters (examples from 1907 through 1997) to make them satisfactorily usable unless there is actual damage. Surface rust is not more than an esthetic problem and if you can't see it without removing panels, then not even that. Sometimes the factory tightened screws on panels where the paint had not yet fully cured and now when we unscrew the screws some surrounding paint comes with them, so then you have a chipped-paint look right on the front.

Yeah, things that were a "press fit" (a machinists' term) are almost never as secure when they are pushed back on. Not to mention the marks that pliers make.

Does you new Model 17 have any actual problems?

Uwe, the first tentative pull with my fingers made me think that they might thread on as you say but, it seems the control rods/bars are flat all the way to the knobs and so do not thread into them.
Years ago I worked in the shop that made the Vari-graph lettering machine.
We used a great many horology tools during the assembly process and one common tool was the 'removal tool'
that was clamped on to what ever shaft, rod or bar and incorporated a forked 'pry bar' that worked against itself to pull off what ever was needed without damage to the part, shaft or machine.
I don't have access to those tools any more so before I go searching the internet for that kind of thing or resort to making them in my own shop, I am asking the forum if there is another way.
What I didn't mention in the thread starter is that there seems to be some slight damage to the bracket that holds the left side of the spool cover in place and also holds the left spool shaft upright.
It seems that the entire type basket, key board, spool drive and related parts may all come out of the body as one unit via two levers on outside of either spool mount.
This would preclude having to remove the faceplate but, there must be more that has to be removed to get the assembly out.
If I can find the right technical resource I should be able to determine  what needs to be done to remove the assembly or just examine it in place.

Wouldn't you know as soon as I logged off the other day, I found a source for TM 37-305, a military technical manual for the maintaining and repair of military issue typewriters from the WW2 era featuring the Remington 17 among others.
What I need to do to gain access to the innards of the 17 is fully described in words and pictures.
Nothing is said about removing the faceplate for this procedure so I'll be tabling that operation for now.
Some more careful examination of the control rods/bars is called for because the edges of the knobs in question are just a little scuffed up like someone may have taken a pliers to them at some time in the past.
Still hoping some one with some additional experience in the matter my come along to enlighten

HABD!! 

Hey, thanks for the help and encouragement on this project.
More research and study has indicated that this machine has been factory refurbished at some point.
While I'm not certain exactly what that all would have entailed it is obvious that the key tops, exterior paint and decals are new/updated.
There seems to be a consensus building that the knobs in question are threaded on to their respective shafts however, what I see so far is that the flat profile of the shaft or operating bar would have to be crimped into a round or at least 'round-ish' shape on the end to be threaded for the knobs.
With the ( I think it's called the inner console ) still in the machine, it is pretty much impossible for me to determine with any kind of accuracy.
It's raining here again so I may have some time this week to remove the inner unit from the body and see what is what.
I'll keep you all informed.

HABD!!