Our GCC's seemed to enjoy having their cage completely rearranged the other day, including taking some toys out that they don't play with and putting some new ones in. They love to explore around and have found new favourite perches
For a long time they didn't have any interest in their sleep tent, I found a new place for it and they seemed to 'discover' it all over again, it's now their favourite toy, not just for sleeping, but for running thru like a tunnel.
I would keep trying with the boing until you find a place he likes it in. Does he like bells? Perhaps you could put some bells on it, or hang food on/in it. Is it a spiral shape? Get one of those fruit skewers and skewer some favourite fruit/veg onto it, and then hang it in the middle of the spiral. If he wants the treat he can only get to it by climbing on the boing. I'd avoid any other treats other than seed/pellets for a little while aswell.