I realize this is an old thread, but it just gave me the answer I was looking for, so I figured I'd say "Thank You" here to SEVENS, Bluedotz37 and other members for some good info.
I just bought a 4566TSW and unlike my 3rd Gen DA/SA 9mm guns this one had an annoying "click" in the SA take up. I removed the slide, cocked the hammer and carefully looked/listened while slowly taking up the trigger in SA, but not enough to drop the hammer. I could see where the drawbar would pop up just a little (the dreaded click) as the trigger was taken up. As noted in this thread, the trigger play spring was not providing the necessary forward tension on the trigger...it had too much play. So I used a pencil eraser to bend it forward just a bit, as suggested by Bluedotz37, to bring it into contact with the trigger and no more click! I'm sure it won't last forever, so I'll be ordering a trigger play spring and rivet soon. Thanks again for the tip. Interesting that this is an issue for the 45s but not the 9mms (of course, I have several replacement springs and rivets for my 3913s, all still in the bag, and NONE for my "new" 4566). BTW, with the exception of the trigger play spring, the 4566TSW appears to be built like a tank - you know a gun is special when you want to clean it (even if it doesn't need it) just so you can admire the engineering and workmanship. Looking forward to taking her to the range real soon.