To the left of the Power Grid entrance is a platform where you can Sonar Shot a familiar switch, the card suit, Diamond. Doing so will trigger a spiraling platform to rise up to another high rise where you’ll see another Diamond switch. Hit it with Laylee’s sonar to move another spiraling pillar your way, raising a door that will reveal a hidden area.
Move through the various platforms and open doors. Watch for the giant rotating spoked pinion that will try to knock you off. The next room will have a bunch of Diamonds in a row, Sonar 'Splosion the
Four club diamonds, and move on to collect all of the tokens, Sliding down back to the floor with seven more coins to add to your pocket (or wherever Yooka stashes all the stuff they grab, I don’t know.)