A gamble slapped on a credit card seven years ago has paid off for John Hooper and Dan Endicott.The friends who grew up in south county started their Good Vibrations stereo store out of a small shop on Chestnut Avenue in Roseburg. A couple years later they moved the business into a larger space on Northeast Stephens Street. Now they are preparing to move into an even larger store down the road at 957 N.E. Stephens.Good Vibrations, which now carries a full line of home and car audio systems, will open in early February in the new space, former home …