Thank you for the tips Jim. After watching the YouTube videos I think I have the E-Unit reassembly figured out.
I had a look at the E-Unit on the 1615. The only issue is a broke plastic "axal" on the E-Drum. The upper & lower finger contacts look good as do the brushes but still need to remove the brush plate, and clean the armature, brushes and brush clips. I am holding off ordering the E-Drum replacement until I have a look at the brushes/armature.