I was given as an exchange a KENPRO rotator. At first it was stuck and hard to rotate but using a long screwdriver as a lever I manage to give it a couple of turns and make it sound like grinding stones!
Actually it was grinding fine particles of mud rain usually falls to Greece when in Atmosphere there is mixture of African dust and rainy clouds!
I clean it last night into my shack so I use the less flammable liquid I could use, White Spirit.
I let it soak all night and this morning using a short haired brush I clean it thoroughly and after a general apply of special grease, its like new one rotating freely.
Photos are not great but can can easily spot the red dust on one side due probably to slight misalignment.