(outdent) Of course, Kevinalewis. The quick answer is probably all the sections...! As examples, here's a start: 
 #Introduction: "The book primarily deals with the transformation, through youth's vigor, of a moribund and slothful community." Is that really how we would describe the action if we hadn't had a lipogram before? Does anyone seriously write like that in an encylopedia? Take a step back and formulate the book's themes without looking at the article, then see how they compare. I think you'll find the word choices stilted. 
 #Plot sections: How is the "Plot introduction" section different from "Plot summary"? How many sections of the current article mention Wright's introduction? The "Lipogrammatic quality" section certainly does. We could consolidate them into a section that lays out Wright's aims with the book. Also, the article suffers from some lengthy quotes that don't seem to be making a point—"Plot summary" contains one without any context. What is that quotation from Gadsby'''s first paragraph supposed to add? I left it in during my cleanup runs a while back, mainly because I didn't know what it was there for. 
 #Characters: Mostly a list. How many of these are important to the plot? We don't need to be exhaustive and list everyone in a Dickens novel; why should we do so in a less important work like Gadsby? Trim the cruft and expand on the main characters. Further, why is the radio station listed in the Characters section? Such organization is what makes me think it would be better to start afresh with some or all of these sections. There are only so many repairs you make to an old car before buying a new one. 
 #Lipogrammatic quality: Logically, this section ought to be more important than Characters. At the least, it should be moved higher. It could be fruitfully combined in a section about Wright's purpose. The phrase "inability to use numbers from six to thirty" is clearly related to Wright's phrasing ("The numerals also cause plenty of trouble, for none between six and thirty are available."). As such, let's either quote him directly or make it more clear—for example, "Wright could not use numbers between seven and twenty-nine because they all contain the letter E"). The riffs on famous sayings should probably mention what the original saying is. (How many readers will know Keats's "Endymion"?) 
 #Criticism and acclaim: The first paragraph reads like a list of reviews selected for their lipograms rather than their content. I really doubt that every reviewer, or even a majority, chose to copy Wright's style. Are any of these reviews adding to our knowledge about Gadsby'', or are they simply showing people like to copy Wright's wordplay? The second paragraph is a mish-mash of works that nod to Wright; there's useful stuff here, but the prose has no guiding thread. -