The only part you don't want to mess with is the clutch assembly you can take the clutch clean off by removing the bolt in the center. the bearing that can come loose and all of the bb sized balls is in the clutch to get that mess apart you will have to press it apart as it won't fall apart which is a good thing cause you don't need to take that part apart just off.
take off the nuts that hold on the clutch and the sprocket use the puller to get the clutch off and the chains sprocket off. Now you can lightly tap the main shaft out I'd use a plastic mallet and knock it out towards the clutch side that way you won't ding the little center shaft that is sticking out on the clutch side the clutches bearing will come out with the shaft and then you can knock out the bearing thats on the sprockets side these 2 bearing are the ones you are probably going to be replacing. did you understand all that? I hope so
This is the part that I took apart you don't need to take this apart just off it presses apart so you should not have a mess like this unless you press these parts apart.What looks like dirt or grease is all them little ball bearings what a pain to put all back together.
This is the shaft you want to remove there is a bearing still on this shaft and its one of the 2 bearing that is possibly causing the squeeling
you will not need to take the engine top end off as all this is the drive/clutch parts on the engines assembly. should not be any supprises as long as you don't take the clutchs pressed together parts apart.The big spring is the real spring that puts pressure on the pressure plate this is the spring that keeps the clutch from slipping. and yes you can take it all apart if you want to clean and regrease it.