I have a mega 16/15/3 bl motor I bought used.I haven't had a chance to try it yet but when I turn the shaft by hand it sorta catches,not like a grind but more like you would expect from a brush like some resistance when you try to put magnets together and there polarity doesn't match-not totally smooth going around.Is this normal?The reason I ask is because I also have a Hacker B20 22s and when you turn it by hand it is totally smooth.Just want to know if this is ok. thanks