Quoted from boilerman:the head has the wood slot and the serial number is 04420
This is Interesting, the serial number has been register with IPSND (International Pinball Serial Number Database).
http://www.ipsnd.net/details.aspx?id=23781
Game: Sing Along
Serial Number: 04420
Submitted By: Lynn Bertera/Timothy Hulsebus
Submit Date: 6/15/2011
Game Part: Complete Game
Country: United States
Comment: The kids still play it. It is great fun.
SerialBot Says: Serial number matches format of a Production Game