Do those hand winches release slowly? The racheting system I'm envisioning for those (having not actually used one, so I'm picturing something related to those ratcheting tie-downs) would work well for lifting but wouldn't lower in a gentle and controlled manner. Also, I personally wouldn't mess with garage door opener springs. So honestly, if anything I'd probably stay low-tech and do a simple pulley or a small block and tackle attached to the milk crate or whatever you use to cradle your carboy.