This is one thing that ticks me off to this day.
The answer is indeed look for some blank space in the Track Pane/Track Controls area of the track you want to move until you get the little up/down arrow cursor...
BUT instead being able to hover over any old blank area you kind of have to hunt around because, at least on my install, the grab points are very tiny and it can be a real pain in the butt to get the cursor to change... especially if you don't have the tracks dragged out vertically very far. Same goes for take lanes.
IDK... lots of context sensitive cursor stuff in Sonar is like that I find. Especially in the Clips Pane with the Smart Tool engaged but the whole "Move Track cursor" in the Track Pane is a totally different issue.
Meh...
Just hover around until you get the up/down arrow then drag. I find it usually shows up closer to the MSR buttons (Mute Solo Record) right around their edges. Helps to drag out the track border vertically so you have more area to hunt around.
Cheers.