Oh, I know about the "chatter" discussion on the 8mm Forum: one of the major threads on the subject there is actually about this very machine! It just ends a while before the machine melted down and I rebuilt it. I "pop" over there quite often and recently passed 2,000 posts.
http://8mmforum.film-tech.com/cgi-bin/u ... 1;t=002888At the time I was in the middle of doing those experiments I mentioned and I found the problem to be so pronounced I thought I could never have a remote speaker settup because the chatter would just be nastier sounding if isolated from the machine's noise. However, changing the guide lessened the problem below the point of even being noticeable when the speakers are very loud.
Maybe it's poor logic for me to imply the wear on the guide
caused the chatter (...assuming I did). Problems often result from contributing factors: the speed of the ship, the place on the hull that hit the iceberg, the brittleness of the steel, the insufficient lifeboat space, the coldness of the water: change any one and the result could be vastly different. In this case I'm really saying that even though we are stuck with the 18 frame separation and the greater vibration at the end of that short lower loop, the wear on the guide greatly reduced the machine's ability to
suppress the chatter.
It's probably also true to say I haven't
solved the problem completely: odds are if you hung an oscilloscope on the audio signal you'd see little spikes at a roughly 24 Hz. rep rate, but oscilloscopes don't listen to movies, human ears do, and my human ears aren't hearing chatter anymore!