Replace the mower drive belt on a 48 inch deck used on a Sears lawn tractor.

This deck was used on a 2004 SEARS DYT 4000 and is 48 inches. Newer decks loop the belt through the PTO pulley. This deck has a drive belt that goes to the 3 mower blades and two pulleys that have a spring loaded belt tension-er. It uses a separate drive belt tied via pulleys to the PTO and deck belt. You engage the PTO belt which then engages the deck pulleys when you engage the deck mower switch. When you try to replace the deck belt with a new one it is about a half an inch shorter than the original because it has not stretched.
Now the trouble is you can't install a new belt just by pulling it up and over one pulley and it is impossible to install a new belt by taking off the tension spring and then pulling the tension spring onto the deck because , as we found out that the spring slips off the screw driver every time you try to use to pull it on and over the spring retainer. The video explains it best.