Welcome.
It will work a whole lot better if you go to part tree or Jack small engine or any other site that has parts break downs.
Locate the parts you are talking about then post a link to the page you are browsing
Then you can either use the Troy Bilt part numbers or the diagram numbers so we know what you are talking about
I you can not find the diagram then post the full model number from the ID tag under the seat so we can find it for you.
if its the drive idler then on the left side of mower, the frame rail just in front of rear tire you see a big hole next to a little hole. thats where the spring goes, hook it to the idler arm and then use a hook or heavy cord to pull the spring end through the big hole and slip the end into the small hole to hold it and release the spring. it takes a bit to stretch the spring so its best to set parking break to slack the main belt so you should make sure the pulley lets the drive belt sink all the way in
