Did the top get warped? Check the rubber seals-they may have gotten damaged or hardened. Yes the pull down lugs can be adjusted to pull the top down tighter. For both the rear and side anchors, simply 'shorten' the anchor lug. Loosen the locking nut and turn the lug the appropriate direction, noting the orientation. Retighten the lock nuts.

For the front, you have to remove shims underneath the lug on the top.