I have noticed of late that the guide bar or what ever you call it, the big rod that goes up and down with the guides on it.

It has been getting harder to raise and lower, well today I took it about are found the problem.

I removed the spring and ball and found that the ball was just full of junk, saw dust and grease like stuff.
Clean the ball and spring and reinstalled it, adjusted it and it is now so much easier.

So if you guide bar is not as easy as it once was you may want to take a look at the ball and spring.