Looking at the parts manual, I see there’s a BJ thermostat for controlling the oven burner. If it’s failed, there will still be a flame – but only a “bypass” flame. Obviously not a full flame when there’s a call for heat.
Here’s what a BJ thermostat looks like:
If that’s whatcha got and the only oven burner flame you’re getting, no matter what you set the temperature to, looks something like what’s in this video –
The BJ thermostat is NOT “plug-n-play”. Once installed, it requires proper adjustments. Qualified technicians know that. If you simply install it without those adjustments, then the oven won’t work right.