Hey, what is a desanco.......and can I use it with a fitting clamp???
One thing I have learned about Moen's are that when you have one with integral stops, you can remove that stem assembly and get the majority of buildup, whether it be a disintegrating dip tube on the hot side or just limescale buildup and remove most of the debri from there.
You need a alternate source of water along with someone at the main shutoff in the basement turning the water on and off to complete the task. But integral stops can catch a great deal of the debri and provide an open shot to remove it in this fashion.
And definitely soak those stems when you get them out to delime/descale them and use plumber's grease on the moving parts/threads so you can make them operable the next time you need them.