need help putting on a drive belt for a scotts s1642 riding lawn mower?

some of this might help. I am in the middle of replacing mine and have it all done but getting the belt back over the idler pulley. That is the only hard part. You will have to remove the deck first per your manual (link attached to download one if needed), then the steering linkage, the brake linkage, and the connection to the parking brake lever. Then look at the diagram on the parts listing (link attached) and re-route the belt. Like I said, the tensioner is the most difficult.
Good luck. Also is a link to some other postings.

http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt
http://www.deere.com/en_US/scotts/serv_operators_manuals.html
http://www.ssbtractor.com/wwwboard/view_all.cgi?bd=lawn&msg=17780

Greg
May 2009