You will probably need a ball kit. Not very expensive. Mine was broke when I got my trailer new.
Turn off water.
Unhook line to back of toilet.
Remove 2 nuts securing to floor.
Looking into the back there are 2 screws, either a 25 torex or 3/8" head screw.
Remove 2 screws, holding base rotate toilet top CCW about 1/16 of a turn.
Porcelain part comes off.
Foot lever is just stuck into a hole in the plastic, at the pivot point pull straight out. It will seem you are going to break the foot lever, but it does pull out.
Now you will see a screw that goes into the shaft end of the ball.
Remove screw, pull short shaft out.
Now remove the ball thing by flexing it and removing the opposite end from the hole in the toilet base.
Now remove the ball thing.
The ball thing and seal come as a set, instructions are in the package. Mine took about 30 minutes.
The above are for a Style II toilet in my 5th
http://www.thetford.com/HOME/PARTS/P...2/Default.aspx