Did anything in her environment or her cage change before she suddenly started bar chewing? It sounds as though something may be stressing her possibly if this is a change in her normal behaviour.
Is her wheel big enough & working ok?
It is only a temporary solution but using cardboard threaded through the bars as FF suggested can help as she'll spend time chewing that rather than the bars.
Whimzee dog chews are a big favourite with hams & that might help a little too.
Do you scatter feed or use a bowl? Scatter feeding or making treat toys out of toilet roll tubes or small cardboard boxes to hide food in can help a lot to encouraging natural behaviour foraging.
Do you have a photo of your cage set up that might help us see if there are any changes you could make that may help?
I wouldn't put anything on the bars, it doesn't work long term & isn't good for them.
If she chews the ball then I would just not use it, it doesn't really benefit her at all, either just use the bath or make or buy a playpen where she can have lots to explore & things to do & you can interact with her at the same time.
If you haven't seen it already have a look at this thread for more ideas.
Managing Bar Chewers