Last September I took delivery of my third Dexcom receiver and system. The LCD pixels on the receiver were faded and dim. I complained and Dexcom sent me a replacement receiver. That receiver had the same problem. I sent an email to the CEO of the company, guessing at his email address. The email included photos showing the degraded quality of the new receiver screens. I quickly received an email from the second in command's executive secretary. I forget the executive's name but he was very concerned with my complaint.
It turns out that Dexcom started sourcing their LCD displays from a new company and the quality went down. I was finally sent a receiver that I felt was acceptable. I pointed out to the executive that display contrast and crispness was very important to those of us with diminishing visual acuity due to aging. He agreed with my sentiment.
I lost track of the issue as I knew that Dexcom was transitioning to the new Gen4 sensor and receiver. I hoped that the new receiver would not have the same problem.
Dexcom knows they have this quality problem with the 7+ system. I recommend that you complain and ask for a replacement receiver. Good luck. Please post what actions, if any, that you take.