Gary, you need to take the big nut of the center bolt and clean the threads up. Then put a 2"+ dia pin in the sprocket teeth and back up. This will force the spring pilot back off the anchors and then tighten up the big nut to hold it compressed. Then split track, unbolt idler ext rod flange from cyl, take off anchors and lift it out.
"HANDLE WITH CARE" you have a lot of force compressed there.
Take to a shop that can the change spring, life is too short.
The pins and bushings have to both be turned, feel the top of the bushings for wear to see if they have been turned.
Replace rollers with used rollers as close to the size of your other ones as you can get, one new roller will wear fast and ride rough.
Later Bob

Thanks again Bob, I am keeping this in a file for when I start!