When I play notes on the low strings, I pull the slide back towards my body so that it covers just the strings I want to play. But, the bar is heavy and I have to change my grip on it to keep it from dropping. Is there a better way to handle playing on the low strings?

The thumb is there to balance the bar straight and to hold it up as it hangs off the strings. I like to have my thumb on the side of the bar towards the end and then if I need to slide the end of the bar off the strings (towards me), or pick up the bar, then the thumb will actually move just underneath the bar to control it better, and the second finger behind the bar pushes the bar against the thumb. So your grip is similar to when you had the bar on the strings, but it will change somewhat, with the thumb working underneath a bit.

-- Ricky Davis