how to remove casing on challenge xtreme 2000w pressure wshr?

I need to remove casing on my 2010 challenge xtreme pressure washer to replace faulty on/off rocker switch. Hve removed screws (3 top - 3 bottom) but casing wont budge !
Is this a "snap fit" ? Don't want to crack it by using too
much force.
Peter Fullagar, February 2020


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