Unless you can cite a source who worked there before I was hired, I can neither vouch for the Carol Burnett story nor the theory that Steve Ryan created the format. To the best of my knowledge Bobby Sherman created the format which was inspired by The Cross-Wits. The only office run-through I'm aware of was videotaped and featured Linda Kaye Henning and Richard Paul. What I can vouch for is that there was a record store called Music Plus on Vine street which was plainly visible from the P+ offices and which had a large plus sign on the storefront, just like the large plus sign used on the show. You don't suppose that's more than mere coincidence, do you?
The show continued for about a year and a half after Allen passed away, which blows the theory that his passing was a contributing factor to its cancellation.
To answer a question from another thread, the reason the chairs on the set were placed on tracks is that originally Ted Cooper intended to use motorized chairs and contestants would enter and exit through openings in the rear set wall on these motorized chairs. This bit of cruft is 100% untrue -- it is a story I just made up -- but I want to see how long it takes before some obsessed Ritalin-deprived fanb0i posts it somewhere as a true fact.