Jim,
I asked Chris, the owner of LMS, about slowing it down and he said he didn't know how to do it and had not heard of it being done.
Both,
Are you guys talking about changing an internal speed pot? The 8.5x20 doesn't have an external pot for controlling speed. It uses membrane buttons to change speed in 10rpm increments. As for 1 rpm, I'm sure you know that could present a motor cooling problem. I have wondered if that's why the minimum from the factory is 100 rpm, for prolonged threading sessions, but haven't found an answer.
Tom