shower diverter stem stuck

help !! I am trying to replace the diverter stem on my American Standard shower... half is out, half is stuck in there detached from the rest of it... I bought special tools to turn and grip and have turned them so much it almost doesn't grip any more... I am attaching a photo ( not too great)... maybe someone will get the idea, though...
please help... I need a shower !!
thanks

That is not the best photo. Have you tried turning the water on in short burst ,this ,,sometimes,,blows those detached parts out .
Cal