Hi there.We have a Hotpoint electric oven that has started to go wrong.It has a digital display for setting functions,but over the last few months,when we turn the oven on,normally the fan comes on quite strong ,the digital display shows red bars as the heat builds to it required temp.What is happening now is that fan comes on,but seems to be with a softer? noise,then never comes up to temp.Sometimes it comes in straight away,other times never after numerous attempts.Other functions like the grill are still working properly,which has me baffled.Xould it be a faulty thermostat,or something to do with the digital control panel?Any help would be great