According to MT-32 Owner's Manual there are five songs stored in MT-32 ROM that can be played using ROM Play -- hold Master Volume while turning on, press part button 1 through 5, press Volume. Sounds nice but I cannot get it to work. Is this available only on newer units? Mine is the older one (no headphone jack), reports version 1.07 (turn on while holding 4, Rhythm, and Master Volume).