There are no resistors on the yoke. Are you referring to the neckboard ?
There should be a number silkscreened on the board where the resistor mounts, like R143 for example. That will identify the resistor in question.
Usually if you have a resistor problem on the neckboard on a 900 it will be either r141, r146 or r143, resulting in a loss of one of the colors.
Those 3 resistors should be 3.3k ohms at 1/2 watt. For some reason I see 1/4 watt resistors there from time to time, they need to be at least 1/2 watt or they won't last.
D