The complaints present two symptoms of a common single problem: the friction condition between the spinning axle and the string loop at the axle end of the string is out of playing range. In the first case, the friction is too low for the YoYo to return; in the second case the friction is too high for the YoYo to "Sleep".
It's usually a good idea to bring the string to its normal "relaxed" condition. Do this by dropping the YoYo to the end of its string, then taking the string off your YoYo finger. Let the string hang loose to unwind itself; it helps then to grasp the string loosely between thumb and forefinger and move the fingers once or twice down the string to further relax the strands. With the string relaxed, try the YoYo again. You should be able to throw an easy "Sleeper" and get the YoYo to return with an easy tug of the hand. If you feel the loop at the axle is too loose, throw a "Sleeping Beauty" ( "Flying Saucer" or "Lariat") to the right to tighten the loop. If it's too loose, throw to the left to loosen the loop. Of course, you can always let the YoYo hang at the end of the string and spin it clockwise to tighten or counter-clockwise to loosen the loop.
A narrow "range of play", where very minor adjustments in the tightness of the loop cause the YoYo to sleep or fail to sleep, is undesirable. The range of play that you achieve, depends on the axle and string that you use. The range is widest (best) when you use a soft cotton string with a relatively soft wood (birch) axle. Hard strings (of fiber other than cotton) and hard axles (maple, brass, or steel) tend to require a tight ("choked") loop, limiting the range of play. Waxing a wood axle can provide longer spins but can also restrict the range of play.
A worn birch axle makes trouble. Remove the string from the YoYo and look for a bright, shiny, narrow groove in the axle. If you see one, replace the axle with a new one, assuming you have a "take-apart" YoYo which allows you to do that. You might extend the life of a worn wood axle by wiping a drop of water at the end of a toothpick around that groove to raise the wood fibers. You can also try that with wood axle YoYos that you can't take apart.
The YoYo string is fabricated of a single strand, doubled back on itself and twisted, then tied with a finger loop. A new, fluffy, cotton string can give you an immediate improve-ment in the range of play. But beware of any string in which the single strand is so tightly twisted that if forms distinct "kinks" in the loop at the axle. If the string makes trouble, you may have to work with it awhile to get those kinks worked down.
A final thought: when you decide to replace a string, slip the loop in the YoYo groove onto the axle, but don't immediately wind the string up to throw the YoYo. Before you wind the string up it needs to be conditioned to remove any kinks at the axle or in the groove. Grasp the string between thumb and forefinger of your YoYo hand about three inches above the rim of the YoYo. Hold the YoYo in the opposite hand; then, keeping the string loop open all the way to your thumb and forefinger, keep a light grip on the string and move the YoYo hand along the string away from the YoYo. Watch the twist in the string redistribute itself down into the YoYo groove! Give the YoYo a clockwise spin to tighten the loop at the axle a bit. The string is now ready to wind and the YoYo is ready to play. This procedure is detailed in the prior article "The String's the Thing" in step-by-step text. Learn it well for best string and yo-yo performance.
Novices need the advantage of the widest possible range of play. That's one great way to open the gate on the Path to the State of YO.