I have had this oven since new in 2017. It has never worked as it should & I have had it looked at professionally 3 times. From day 1 the flame would not go very high & food stuff would not cook sufficiently & it took an age. I had it checked out & was told it reaches the temperatures, but it takes ages to get to them. I persevered for 3 years before asking a different engineer if he would check it out. He found metal fray in the burner & cleaned it out. It was fine for about 5-10 uses then the flames dropped again & it was useless. I had another engineer look at it again & he found gunge in the Jet. Cleaned it & all was good again for 1 use. As you can imagine I’m now annoyed having to keep paying out so I bit the Bullet & looked at it myself. I took the Burner out & all was good. I was unsure of going further & I didn’t want to take any risks with a gas appliance so I just poked around gently inside of the Jet & low & behold it did the trick all working good again. About 3-4 uses later it fails again. This time I ain’t messing around any more & I got spanner’s & removed the Jet & found a piece of what looked like fray wedged behind the Jet on the gas pipe side. I removed it & put everything back as it was. Now the oven lights with a very strong blue flame but it doesn’t adjust from the knob. I tried leaving it to see if it automatically drops on reaching the temperature but it didn’t. I cleaned the Thermocouple lightly with emery paper which didn’t improve it. And that is where I am at now. Can anyone throw any light in this please?