Plugins, particularly adblockers, can cause this quote button failure as well as deprecate other site functions. They're just not very good at telling what's an ad and what's a site feature.
That's it !!!!
Thank you, disabled Adblock 2.5.1 and back to normal, so now I have to make a choice ! Do I want Ads. or a Quote button !
Doesn't answer the question tho' - why did Adblock suddenly start to do that, it had been installed sometime ago ?
No matter, problem solved.