What are the main analysis required for checking the performance of Ion exchange resin in a condensate polisher? The Condensate polisher/ demine...

What are the main analysis required for checking the performance of Ion exchange resin in a condensate polisher? The Condensate polisher/ demineralizer ion exchange resin performance has been reduced suddenly although the resin volume is not changed, also influent water quality is  unchanged and Regenerant conc, flow. rinsing, etc., are not changed (Regeneration process is going properly) so we suspected the ion exchanges resin might expose to a physical attrition or degradation which results in loss of performance. If the  previously mentioned parameters are constant. Is Ion exchange resin need a further analysis? If so, What is the major analysis required to check the resin performance? Kindly submit your point of view.