Noel,
That is a nice machine. I like it.
Sew-Classic has the thread guide towards the bottom of this page: {
http://www.shop.sew-classic.com/Misc...teners_c26.htm } You might give her a email to see if she has a screw for it.
The thread guide screw also doubles as the needle stop on many machines so it is an important part.
The knob, if it's still functional just needs a cover disk. Were that my machine I'd fabricate one rather than replacing the whole knob.
Joe