LG Dishwasher, loud noise on rinse cycle

[ZMan]

During the rinse cycle, I get a loud revving sound. At the end of the cycle the motor has no problem pumping the water out of the machine. It sounds as if it’s trying to recycle the water during the rinse cycle. I have downloaded the repair manual however I’m not clear on what may be broken. I have in gotten the E1 error on occasions, I’ve checked for leaks etc.

Can someone point me in the right direction; is it a gasket, impeller, or the pump motor? I have a feeling it may be the impeller, however does anyone know if the impeller is used when draining the dishwasher, because that appears to work fine.

One other quick question, how do I get this LG LDF7811ST dishwasher into test mode. Do press Rinse + Time Delay + POWER S/W then the mode?

[BrntToast]

drain is done by a seperate pump
common LG noise problem is the impeller but first check the macerator(chopper blade) it is labeled "this side up" and apparently the korean assemblers could not read this english instruction and were putting them in upside down, found many is backwards while doing LG warranty