Sadly the 20 inch Series II machine was destined to fail from day one. There's just way too much span for the rails to flex over and thus as you have noticed the single piston engine just needs to be solidly secured down. The rails really required to be much thicker right from the start, but then I don't think SB anticipated that these machines would be around nearly 50 years later, so really they haven't done that bad really.
Have you seen the following two photos ?
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
