Well, after studying the problem and re-reading the manual, plus looking at some pictures on the internet I realized that I had been assuming that he ring was used on the plunge base, because that's the way DeWalt had designed the DW618 routers. Although I had read the manual for the DWP611 several times, I somehow missed the one important sentence in the whole manual that said this, and since no pictures exist in the manual showing the plunge base assembled without the ring, I must have been confusing myself by remembering how the DW618 plunge base was designed, as you are supposed to use the ring with it.. I had even talked to DeWalt Customer Service and they weren't any help, but offered to send me replacement pieces, that in the end I didn't need. It wasn't until I finally found pictures of the 611 plunge base and motor assembled without the ring that it dawned on me that I wasn't supposed to use it. Duh !!!
The barrel clamp on my plunge base was very loose from the factory and needed tightening before it would hold the motor in place too. It's becoming important to check all screws in everything you buy lately, to be sure they are tight, and I failed to do this, until last night. I'm all set now and my plunge base is working properly. I even used it last night.
Thanks everyone for the help.
Central North Carolina