We all love eccentrics
Mostly used by Kawasaki and a few others. You’ll need a tool to suit the spindle end caps (often a hex-key) and to undo the locking bolts. Undo these and turn the drive-side end cap so the spindle rotates until you have correct tension. Check the end caps are adjusted equally — the spindle usually turns the other side at the same time but check. Tighten the lock bolts back up.