Flason take the case off and find the rear of the knobs,Get some wd-40 and spray them with this,turn controls back and forth a few tmes and your all set,Wd 40 will clean all dirt and dust away and then will evaporate,Others will not,You do not want a oil to stay wet inside your unit,and thats what others do.This will only collect more dust and dirt and cause more problems in time.This is only a good tip,But thats up to you !