Ouch.
Was it rusted at all. I used to have one like that (actually I have been through two like that) and the various parts started to rust and mine you buckle and then the canopy would begin to fill with rain, which buckled it more, collecting more rain, leading to more buckling, etc. I beefed it up a bit by welding in some random steel stock I had laying around, and then it buckled in a different spot. I was just chasing my tail with it.
I have one of these now -
Sojag Sanibel II Gazebo 10 x 10 ft. 500-8162851 | Zoro
I really don't think I paid that much for it though. I have had it for almost 3 years now and it is going strong. It will probably outlast me.