How to fit water filter to Russell Hobbs steam iron?

I have a manual and it says you must change while the base unit is plugged in and switched on, otherwise won't register the new cartridge. But turn temp control down as far as it will go and let it cool. Tuck towel under front to absorb leaks.Remove water reservoir. When cool,use one hand to steady base unit, then fingers of other hand up and under cartridge tray (its at very front under where reservoir was). Pull out cartridge tray, tip old cartridge into sink, and mop up base unit. remove packaging from new cartridge, drop in tray, replace tray then reservoir. Check that flashing cartridge light has gone off - if not, tray not in properly

VB
March 2012