Update 9/14/20: The Google Search Console tells me this is my most popular page. You may also be interested in my post regarding mod parts for the G900/G903.
If you are still using a Logitech G900 or G903 mouse, I highly recommend replacing the switches with either the Omron D2F-01 or D2F-01-F. The D2F-01 has a higher actuation force which provides a more tactile and satisfying click than the original switch; personally this is what I’m using. The D2F-01-F has the same actuation force as the original if that’s what you prefer. The reason you’d want either of these switches is because both are Japanese Omron switches which are considered higher quality and more reliable than the original Chinese Omron switch (D2FC-F-7N). It seems the Logitech G903 and their newer mice are notorious for double-click issues; just Google it or take a look at the /r/LogitechG and /r/MouseReview subreddits. These YouTube videos go into great detail to explain why newer mice fail so often and cover different switch types: https://www.youtube.com/watch?v=v5BhECVlKJA and https://www.youtube.com/watch?v=NhhRTUrz0R8.
The Logitech G900/G903 isn’t too difficult to take apart but there are quite a few screws to keep track of and they are not all the same length. Be sure to have a spare set of replacement mouse feet since they must be removed in order to open the mouse. Here’s a list of YouTube videos that detail tearing down the Logitech G900/G903:
I also took some photos while taking apart my G900; hopefully all of this info will help you upgrade your mouse with new and better switches.