Thanks Shawn!
I will give that a try. Unfortunately, my first problem is that the handle is also frozen on the horizontal shaft which rotates the locks. I've unscrewed the handle from the inside but can't pull it off. I've thought about securing a small impact dent puller to the handle and, with someone holding onto the shaft from the inside, gently trying to break the lock free. Penetrating oil sprayed in from the back side might work too. It would be great to able to lock the canopy.
Have a great weekend.