Repair is a 5 minute job, however this time (4th element in 10 years) the old element burned out with a huge arc welding flash for 30 seconds filling the house with smoke, leaving a residue and welding splatter in the oven and frying the connection wire which had to be replaced which involved removing the convection fan. Why do they only last 3 years? We do use self clean a couple times a year. How long will this one last?