try this method for descaling: https://www.wikihow.com/Clean-a-Keurig-Water-Reservoir
Have you tried hot/warm vinegar. Here is a tutorial video that should help you https://www.youtube.com/watch?v=ZCpbqSMGS0w
Hi Mary. I use vinegar and a small old tooth brush.
My unit is removable. I just take it off and wash with Dawn and water.