Likely the key lockout isn't resetting like it's supposed to upon carriage return - the little part you mentioned. Cleaning and light oil on the friction and pivot points of that and the margin stop assembly usually can get things moving again. That's the most common issue I see in Royal Standards.

Pearl S. Buck and the 1930s RoyalStandard (with white keys) she used towrite The Good Earth, Jack Kerouac’sroad-weary Underwood Standard S,George Orwell’s Remington No. 2,Patricia Highsmith’s Olympia, Marga-ret Mitchell’s Remington No. 3 (whichher husband bought secondhand andshe relied on to type Gone With theWind and countless pieces of corre-spondence with fans).