This is probably a long shot but figured i'd throw the hail mary anyway:
I just realized I can do the 35 degree oven temp calibration on my kenmore gas range. I turn it on by pressing bake, turn the temp up to 550 then hold bake until a "00" pops up, then arrow up the number of degrees you'd like to calibrate. I went with 35 but when I went to let it reheat my oven thermometer wasn't even breaking 550, let alone 575. Wondering if anyone has had sucess? I know a lot of the models make you press a start button (which mine doesn't have) so wondering if maybe I'm missing a step or something