It is a feature =@) the barrel won't rotate easily. I'd think KEH would do as well as anyone, the lens isn't that hard to work on.
Right now I've got two here a 3.5 and a 2.8 both are stiffer than any other lens I've got.
If you use the lens a lot it will loosen without spending the extra $$$. I have a friend who used a 3.5 for several years as his only lens and it could be focused by rolling the barrel with one finger. Talk about loose.