How do we take the top off an SUK61MFX easily?

Have replaced the back element thinking that's where the problem lay but still no heat. Believe it to be a fault with the oven/grill selection knob but, the oven heats up on all settings except when in the top left position i.e. the fan oven on indicator light. Light on, fan on but no heat. Have never had an operation manual so not even sure if this should never be used on its own anyway. Used this way since 2001.....
Problem is that the last time my husband took the top off he had a terrible time because of all the plastic clips etc. He wonders if there is an easier way to get at the back of the switches.