How to identify worn out guards on a sickle mower

I have been searching this, but cant find a definite answer. I have an IH 1300 sickle mower, that does a good job. However I believe I have some worn out guards. They are stock IH double guards (single at shoe). The edges are rounded somewhat and no longer have the serration I see on some of the new ones. Also the cross bars show wear.  I cant seem to find pictures of worn out ones to indicate when they should be replaced. Can anyone help?

 

I cut mostly grass, with some clover and alfalfa mixed in. If I were to just go ahead and replace them all, what guards should I go with? I think forged would be better than cast, correct?

 

Thanks for any thoughts or suggestions.

Keith

How to identify worn out guards on a sickle mower