I have a 1J step pulley BP mill that I have finally powered up and
tried out. I have tried all of the direct drive gears and it works
well. Wehn I shift in the backgears, it locks everything up tight.
You can definitely feel it shift the gear train, but something must not
be releasing as it locks the spindle. My assumption from looking at
the parts diagram is that the cone drive is not being disengaged
resulting in a locked state. Does this sound logical? Or does someone
have an alternative theory?

Thanks

JW