Use supports until that won't work anymore. That tower looks like my first tower that I still have. Part of it broke off and I discovered the sisal columns had cardboard underneath and not wood.

Jane loves my blue tall tower. It's high and she sleeps and plays up top. It's holding up otherwise.

Your tower does have bolts that can be tightened but not if the sisal columns have become separated from the plastic supports.

Good luck.

Girls, if meowmie gets you a new tower, insist on all wood.