Here are the instructions for a WFF1200 they may be similar. You will need various screwdrivers including hex. It will take about 1.5 hours if you are not expreienced, but is pretty easy.
1. OPen door and unclip metal loop from front on gasket - it has a spring on it so can stretch off.
2. Unscrew front of machine (2 screws bottom, 1 at top under powder tray)
3. Inner metal loop is fastened on by a screw on the right side. Loosen this and take off loop.
4. Examine how the gasket is fitted before you remove.
5. Attach new gasket, should slot on securely by its self so you know it is place.
6. Add the metal loop again and tighen screw.
7. Screw front of machine on again
8. Attach gasket to outer with sprung metal loop. like fitting a bike tyre.
9. jackpot your washing again
AK
December 2004