Hi
@Blues Writer -- Great advice from
@thelastONE !
I had the typewriter itch about ten years ago, and geting back into it now. In any event, the Praxis 48 is a solid machine, so this is likely just a case of something getting knocked out of alignment (happens to the best of us when we start poking around - it's like typewriter curiosity fee!

).
A couple of additional things to try: First, with the carriage all the way to the left, gently move it by hand across the full width to feel for any spots where it catches or feels rough - that can help pinpoint where the issue is. Also, check if your margin release button is fully releasing after you press it - sometimes they can stick partially engaged.
@thelastONE commented on this.
If the 'whirring', as you stated, happens specifically during the return stroke, try typing a few lines normally first, then use the carriage return lever with steady, confident pressure rather than a quick flick. I find that older mechanisms sometimes just need to "remember" their rhythm.
And here's a weird trick that works for me: try setting your margins to completely different positions (like way left and way right), type a line, then reset them back to where you want them. It's like giving the mechanism a little 'reset stretch.' (Like an iPhone hard reboot?!)
I do not own a Praxis 48, but have read it has a reputation for being reliable (once working), so don't give up! These vintage machines just need a gentle nudge to get back in line.
Ezra