Return it. A brand new router plate should arrive absolutely flat and in perfect condition.. And, you will never quite trust the thing.
You might also consider getting a Triton TRA001 router, which has a built in lift and probably costs less than the lift you are unhappy with. I had a lift, but got rid of it and went with the Triton and a WoodPecker's aluminum plate, which is overpriced, but very nice because of its twist lock inserts, which can be ordered in any number of opening sizes. I don't know what you paid for the JessEm, but the Triton is about $289 on Amazon, and a Bench dog plate is about $45. The JessEm on Amazon is about $345.
The Triton TRA001 is a terrific table router so I retired my 1617 to hand held use. No regrets and I like how powerful it is. My thoughts on the matter at any rate.
The more I do, the less I accomplish.