We have a tub shower (in a house built in 1992) that has a Delta faucet/valve with a clear acrylic handle (not round knob--a lever that one can grasp with fingers curled around the whole handle with your fist vertical) with a chrome end piece. How do we get access to the clear acrylic handle cylinder to remove visible black (mildew?) build-up inside the clear cylinder? Sandy/George ph 503-751-1595