Snug
Experiment with the two little screws. If you get the tension one right, you never really have to worry about the lock one - but the tension may well be different for light eyepieces versus heavy eyepieces (a heavy one can make the focuser draw tube slide in by itself, if the tension is too low). Also when it gets a bit dewy and colder, I find the tension one might need tweaking a bit.
'Ain't the heavens great!
Eric
