Wire sticking to nozzle can be caused by several things.
if your wire feed "speed" too slow, it can stick to hot side of feed(burn back).
Some others are- not enough amperage, too much amperage, (most common)dirty weld area(rust, paint, and general junk) causes HAZ (heat affected zone) to get wonky and throws out all the trash which collects on the nozzle area, and eventually causes sticking.
Also lack of,or incorrect protective gases around HAZ.
Solution- first clean nozzle, then stick tip in jar of petroleum jelly. It will reduce "build up" on the head. Keep a jar of Vaseline in the welding cart.
If you are using "flux core" type wire,rather than gas, it by nature throws off a lot of crud. It a nasty business.
TLee