This question has been asked before without anyone providing a link to a manual. My search only turned up 3 fraudulent sites claiming to have a manual, for sale, but my years of experience with similar sites made me avoid getting deceived.
The free youtube video below has a comment that it helped someone who had a Nelco 344c, so it may be of help to you.
https://www.youtube.com/watch?v=3V4vifOaqCo
Feb 14, 2013 ...Ricky Nelson. Long before Justin Bieber or even Ricky Martin, there was the original teen heartthrob. His name was Ricky Nelson. Nelson began his ... " Bimbo", "Four Walls", and "Billy Bayou" but may be best known for songs that he recorded just prior to his *****, "I Can't Stop Loving You" and "Make the world go away....
Jim Reeves had more to do with Bimbo than Ricky Nelson.
You can Google this and get an answer.
My wife is a Ricky Nelson fanatic and she says absolutely no way he recorded Bimbo Bimbo. She has all of his records, albums, tapes, CDs and song lists.