Unplug it!!
Remove the rear panel from the dryer, sometimes its simply the lower access panel sometimes its the whole rear panel.
Look for the motor which will be at the bottom somewhere and next to it will be the capacitor. In my case the old capacitor was silver and metal and the new one was white and plastic so don't worry if they don't look the same.
Before you touch it use a metal screwdriver to bridge across the connections and short it out, a capacitor is basically a battery and stores electrickery and can give you a warm tingly feeling if it is still 'charged' and discharges into your fingers!
on the other end from the connections is a 13mm nut which needs removing to get the capacitor off.
Now disconnect each wire one at a time and reconnect onto the new capacitor in the same position as it was on the old one (hold the capacitors side by side and move one across at a time).
attatch the new capacitor with the 13mm nut.
replace the rear cover.
Plug it in and find out its motor thats gone as I did! lol. if it was the capacitor at fault then it should work fine.
Steve Walker, January 2009