My son just got a 2001 Escort ZX2 and just after a few days he threw his drive belt. This is the one that goes every which way around a bunch of totally inaccessible wheels to drive the air conditioner, power steering and alternator. Don't be too confused by the belt. It's actually easy to figure out when you think about the smooth wheels and the slotted wheels. Anyway I put on a new belt and found out that my tensioner was not quite in alignment and figured "Oh well".
The belt lasted about 2 hours and came apart in two strips along with the entire tensioner.
If you look at the picture you can see that the replacement tensioner is more robust than the original one. It mounts between the power steering and the A/C pulley.
You can probably replace the tensioner without removing anything except the cardboard stuff. However I have big hands so I had to also remove the power steering hose bracket that Is attached to the body and really gets in the way.
You will need a small 10mm ratchet because there is not much room in there. First jack up the car and remove the wheel. Be sure to use a jack stand plus the jack because the break rotor can wind up right above your chest. be sure to oil up the three 10mm bolts before you replace the tensioner. I needed an extension on my small ratchet to get enough torque. The new tensioner can be compressed with a 15mm box with an extension. The last pulley should be the A/C because it is the most accessible. My son had to help me slip the belt over the A/C pulley and he needed a screwdriver while I held the tensioner fully compressed.