R19 and R8 are the resistor that set the current for the 10M90S. a value of 650 would probably be around 3-4mA, just going from memory of the datasheet. so you can calculate its power would be very low
to measure its value the power needs to be off. if you are still measuring 19 ohms then lift one leg of the resistor and measure it. if you now get 650 ohms you probably have a bad 10M90S