Stable (meaning, not continually fluctuating) non standard speeds can occur for various reasons. My modified reproduce only 3 head Ampex 440 (full track, 1/2 trk, 1/4 trk) runs at any speed between 1.5 ips and 45 ips. And, the speed is digitally confirmed to as m,any as 6 specific figures. Best Regards, Art Shifrin www.shifrin.net