Whirlwind would've originally used the type with much more of a pointed plunger end, which continued well into the Wpc era, including the early Fliptronic/II games. I didn't take to the new arrangement, and continued using the pointed type. But putting a conical spring in with the newer link on later games (to obtain the 'feel' I preferred) often resulted in it getting broken, and fouling the flipper return.