Reported the Convection Oven pilot would take a while to light then it would take a while to kick in to heat and when heated, customer noticed a 75 degree difference from center to rack below on left hand side. adjusted spark ignitor and flame switch and unit now ignites on first spark and kicks in to heat within 15 seconds. put two temp probes in one at each location mentioned above. found only 4 degree variance. unit heated and cycled ok. note for customer: pan placement can sometimes change the air circulation causing uneven cooking. also checked temps on bottom oven. temps good on both.