I expect that you have found this:
Elburn
The Elburn Piano Company built pianos for the large retailer J.W. Jenkins Music Company of Kansas City, Missouri. They built medium grade and high grade pianos from about 1910-1965. The firm offered a full line of upright pianos, player pianos and baby grands up until the Great Depression era, and then they incorporated spinet and console pianos into their product line in the early 1930’s. Elburn pianos were distributed mainly throughout the mid-western United States, and are a bit uncommon in other parts of the country today.
http://antiquepianoshop.com/online-museum/elburn/
I can't say that I know anything at all about the company and may take the phrase "medium grade and high grade pianos" with a grain of salt. Chances are good that they were durable instruments, but if they were truly high grade their fame would have reached beyond the American midwest and the J.W. Jenkins Music Company.
Here's an interesting on J.W. Jenkins
http://www.kchistory.org/cgi-bin/showfile.exe?CISOROOT=/Biographies&CISOPTR=242&filename=243.pdf
Edit: (This, from a legal pleading -
The J. W. Jenkins' Sons Music Company v. Armstrong-Byrd Music Company - chances are good that your Elburn was made by Cable)
The plaintiff and defendant are both dealers in musical instruments but neither manufactures them. The plaintiff maintains its principal place of business at Kansas City and branches at various other cities, among which is Oklahoma City, where the defendant also has a place of business, and is a competitor.
It is undisputed that the plaintiff first adopted the trade- name of "Elburn" for pianos, taking the name from a town in Illinois, where the president of the company and his brother were born, and the purpose was to build up a lasting trade under that name. The first piano bearing this name was made for the plaintiff by the Cable Company in 1902, or 1903. Two other companies also manufactured pianos for the plaintiff which were given the same name, to the number of less than thirty and one hundred and forty respectively. With these.exceptions, and a few afterward made by one of them in 1906 or 1908, only the Cable Company has made these pianos for the plaintiff, and in four different styles, according to direction furnished by the plaintiff. The name, "Elburn" and the words "Manufactured expressly for the J. W. Jenkins' Sons Music Company" appear on the plate, and the name also on the fall board.
The plaintiff employs twenty-three to twenty-five traveling salesmen and advertises in the newspapers published at its places of business. During the past five years, these "Elburn" pianos were widely advertised at heavy cost by the plaintiff, and became well known as plaintiff's pianos to the trade in the southwestern part of the United States and largely to dealers elsewhere, the total sales reaching about five thousand. They are guaranteed by the plaintiff and sold at a fixed price, except that reductions are made to ministers, churches, lodges, and certain classes of musicians.
Learning from a circular and newspaper advertisement that the defendant was selling pianos bearing the trade-name "Elburn," plaintiff applied for membership in the United States Trade-Mark Association. That association wrote the defendant under date of April 27, 1911, asking that it cease to use the name "Elburn" on pianos, to which the defendant replied by letter of May 1, 1911, that it was not selling the "Elburn" pianos under any trade-mark or making any claims for it further than that it was a stencil piano and that they would continue to sell and advertise it at the price at which it should be sold as long as they should be manufactured and sold to the defendant. Reference was given to its attorneys, and the letter concluded:
"We have looked into this matter carefully and know exactly where we stand and knew exactly where we stood before we ever went to advertising the piano for sale."
Plaintiff then employed counsel to bring this suit and another against the manufacturer in Chicago of which the defendant purchased the pianos.