Quote Originally Posted by runsusie View Post
. . . it looks like I need to pull up on the center buckle and push the two side levers down to release the clamps from the groove in the rubber strap,
PW and Kermit have it.

Push the two side levers down, then pull up the strap over your foot.

Pulling up on the buckle tightens the strap, notch by notch.

Also, to micro-adjust tightness while you're riding, push down on only one of the side levers. It will loosen a half-notch.

If you walked through grass at some point, you may have gotten a bit lodged into the buckle (which is why sometimes I get stuck in my mtb Sidis) so good luck! No, just keep a dental pick or something thin and pointy handy in your car or garage to dislodge the bit when you finish, then you can loosen the buckle again.