This is why manufacturers like you to register the products within thirty days. It covers their backs and does make your life easier if you need to claim.
£64.99 for me
Got 3 sparks/spectrums and none have ever had sticking keys. They have, however, had RGB issues on keys. Would agree about Logitech support though, has been truly awful for me over the last 7 or 8 years, including once for an aforementioned G910. The main reason why I'm weaning myself off Logitech products these days.
I don't blame them in not being as customer-friendly as they used to be. I sold a keyboard on eBay some years back, and had someone message me asking for a photo of the serial for what seemed an odd reason. Did some digging into why, and found an entire forum dedicated to buying/selling Logitech serial numbers, for the purpose of ripping off Logitech by using false warranty claims for free 'replacement' products.
Because the keys start sticking and double typing just out of warranty and Logitech isn't as customer firendly as it used to be, so they wont do anything about it. Avoid anything with Romer switches.