Click on the Play Button to stop or start a LoopTrack. Hold down the right button to pause the loop, and relase to unpause. (Stopping returns the LoopTrack to the beginning of the sample, pausing does not.)
If the Play Button has a red dot in its centre, then the LoopTrack is not thinnable . To toggle a loop from thinnable to unthinnable, double click on the LoopTrack's letter.
Note: changes to the Gang are transmitted to all LoopTracks controlled by the Gang. Changes to the master LoopTrack in a blocked Band are transmitted to all LoopTracks in the Band. (This doesn't apply to thinnable/unthinnable.)
Also see: Doing Things with LoopTracks