I used to be in management with Bill Knapp's in the mid to later 80's in the Dayton and Chicago area. Somewhere in my stuff I have some menu's, including an original 1948 one, probably some old employee schedule tablets, name tags and who knows what.
In my opinion when I was in Chicago I saw the beginning of the end of the company. They bought very expensive real estate in upscale neighborhoods for the 5 units there. They were the newer large open kitchen design, the exteriors where immaculately landscaped. The people of Chicago came to the grand openings dressed up expecting fine dinning, what they got were the original yellow uniforms, the diner style china white with the green boarder. The busy openings soon trickled off as confused patrons didn't know what to make of the new restaurant in town. The company's reaction was the "new concept" where they introduced the new china, the new uniforms, and broiled food. Bill Knapp's as a company literally forgot who they were. The irony of all this was at the same time as this in Chicago Ed Debevic's was very popular (it was a throw back diner)
While I think the broiled food and fish items were a good addition, the real problem was growing overhead as they then expanded into Florida and there also bought expensive real estate, they repeated the mistake over 20 more times. This increase in overhead soon began to drag on company profits. The "new concept" was expanded company wide and now some of the Midwest customers were getting confused. They began direct mail "discount promotions" that built business during the promotions, but resulted in low sales between. They were trapped in a discount/promotion cycle. Meanwhile it was decided that the pure white buildings looked to formal, so the Arlington Restaurant was the first the get the new cream with maroon and green exterior paint job, but on this building they even put a new real wood shake roof on it! The new paint scheme was expanded company wide, so another big expense was put out repainting all the buildings. Another building got an exterior "fix" for it's sales problems was the Miamisburg unit outside Dayton. The put a new large glass cupula on the building, making it more like a light house, didn't work.
It was plain to see the company lost it's identity. During all this confusion (Jerry Hill had already retired) the new top management was putting on the squeeze to cut labor costs, and the restaurant industry was becoming far more competitive. It's a sad tale. I contend had they gone back to basics, built new small restaurant buildings on leased parking lot spaces they could be a success (kind of the way Steak 'n Shake has been revived).