First, thanks to Patsy! I was beginning to think I was the only one nutso enough to do this!
For TCCBass: Gentlemen? Patsy, are you a Gentleman?
To remove the tethered cap from the sender, you need to depress the clips that hold it on. You will see two or three of them on the sides of the unit. Look for two parallel "cuts" in the plastic barrel for each clip. depressing these gently while pulling the cap off should work. You might also get the "clips" to grab the threads of the cap and be able to unscrew it? I forget exactly how I got mine off. All I really remember was that it seemed to be impossible when I was concerned about damaging it, and easy when I wasn't...