I have a Logitech G710+. After years (like 8) of use, the keycaps were starting to crack with age. I reached out to Logitech and they sent me all new keycaps, free of charge, despite being several times past the warranty period.
Truly amazing customer service.
did you ever watch the youtube 'deepdive' into the double click?
Turns out they are using an older switch which, while great at the time, wants a higher voltage than modern, electricity diet, mice.
https://youtu.be/v5BhECVlKJA