Replacement convergence/purity ring set...?

[nam9]

So, I have this Tatung monitor that may or may not have been bumped in shipping..
The purity rings are loose - one of the small black tabs that hold them in place has snapped and now they slip off towards the screen.

How do I go about rectifying this issue? The rings are a complete, separate unit - can I replace with any suitably sized 6-ring set?

Thanks!

 

[nem]

Try asking on Arcade Otaku.