Roger has it correct. You need to pull the unloader to the top of the silo before filling it. The unloader is just for UNLOADING. LOL.
There where very few that actually leveled the silage as you filled. I have heard of them but never saw one.
While the silo is empty you need to check that unloader out as it will be at the bottom. Where it is much easier to work on. The cross auger/augers need good flighting to cut the packed silage. They may have little points on the flighting's edge to help cut the silage. Some do some don't. Then check the blower housing out to see of it has any holes in it. Then check to see how close the blower paddles are to the side of the blower. I always set mine where it would catch a nickel but drop a dime. (that is the thickness needed for clearance on the ends of the paddles) Also check the drive belts out. If they are not real good replace them now. Because they will fail on the coldest morning you have. Make sure the motor starts and runs OK. Make sure all the grease fitting take grease. I have a grease gun mounted on the blower. I grease them every time I move to the next lower door. LOL.
Truthfully you maybe better off to call around and find out who does silo unloader repair and pay them to come out an check it out. They will know what to look for. Then they can show you first hand how to set the blower up to raise it and how to set it to unload.
As for filling your silo. Your blower neck should have a deflector on the end that gets turned down into the roof when filling. Both of mine have a cable that runs down the outside to where the blower sets. There is a lever that adjusts where the deflector is directing the silage. You do one load against one side and then the next against the other side then do one in the middle. Then when done you level the top off by hand. They do make Plastic covers for to seal the top so you have less spoilage while it is going through the ensilage process.
CAUTION!!!!! When you enter the silo to level it off have the blower running for a while before you enter the silo. I usually level mine right after I put the last load in. If you let it set there can be silo gas built up. That gas can be poisonous. It is usually heavier then air. So I always go above the door I am going to open and open it while being above it. That way if there is any gas it will go down the chute. You just unlatch the door and then climb above it and kick it in with your foot. Then wait a little bit and go in an level the silage.
Generally a silo unloader is the poorest maintained piece of equipment on the farm. They are out of easy reach and in an acidic environment. A cheap one is usually just a headache waiting to happen when it is cold and nasty with your cattle waiting for feed. I use mine because they are already here. I would never build another one. I can feed much easier and safer with silage in a bag or pit.
If you want to talk to some one email me and I would be glad to walk you through some of the issues I see coming.