I know nothing about the flame sensor...but, for the TC...
A TC works by generating a small voltage, in proportion to it's temperature. This voltage can only be generated if there is a sharp change from one materiel to another. Over time, this 'seam' degrades.
First check the TC fo continuity. If good, than check for a steady voltage between the leads. If the voltage fluctuates, or the meter cannot seem to settle on a value, then the TC is probably bad. Ditto if the read-out on a TC meter bounces all over the place.
