To change the ring, you need to dismantle the upper and middle part of the grinding mill. Using a crane, you can lift the middle part.
At last, you left the part of the one on the picture, you can change the ring and roller.
Roller Assembly Dismantle
If you do not want to change the ring and only want to change the roller, you can dismantle the roller assembly directly from the inspection window. As is shown on the picture, you can get the roller assembly out from the window.
For the roller, there is a screw and nut under the roller assembly. First, you get the nut out, then dismantle the roller. When you change the new roller on it, you can use a hammer to hit the roller to the right place. At last, you use nut to fix the roller.
For the ring change, you need to screw off the nut which used to fix the ring first. Then get the ring out.
Shovel And Shovel Base Change
After you get the roller assembly out, you cant change the shovel and shovel base accordingly.