Coffee not hot enough. I have a Bunn coffee maker. The hot plate does not keep the coffee as warm

Question

I have a Bunn coffee maker. The hot plate does not keep the coffee as warm as the coffee is right after it brews a new pot. I suspect the thermostat is loose or malfunctioning. Is there a test procedure or an adjustment I can make to warm it up? Is there a parts supplier out there from whom I can get a new thermistor?