I think you might be right. We started making our own concoction of dishwasher cleanser...kosher salt, vinegar and a squirt of dawn... thinking that would save moolah! now as I think of it, since we started doing that...it started whining.
gonna go to the store and get regular detergent and see if it fixes it!
I am back! so now our whisperquiet machine is not so whisperquiet... makes kind of a whirling up and down sound, like its annoyed it has to work, and we are starting to get black flecks of greasy bits on the dishes and glasses. Methinks its the rubber seal deteriorating. I have cleaned the filter out. curious what this might be.