First off, a very quick google search of the NSN for the resistor shows that it is a 56 Ohm, 6.5 watt resistor. If your guy came up with anything different that that I would go by what the NSN shows. Here is a link...
5905-00-081-7350
As to the start disconnect switch, I cannot vouch for the operation of that switch because I've never even noticed it on the prints before. However, looking at the prints I doubt that it has anything at all to do with that resistor. That switch looks like it prevents "K3" relay from energizing, without "K3" you cannot energize "K6"..."K6" is the starter solenoid. Even after the set is running you can still hit the start switch and get the starter to try to engage, so that switch does not open when the set is running. Meaning that it is always in the circuit with the resistor, just allowing the resistor a path to ground if needed.
More than likely, what has happened to your resistor was that someone held the start switch too long in the start position. When the start switch is engaged terminal 27 of S1 has 24 volts on it, which in turn through the wiring feeds the exciter field to start the generation process. The resistor provides a means of voltage drop for that 24 volts so you do not over excite the field in the initial stages of start-up (by holding the start switch too long you are putting more power across that resistor than it can handle and it burns up). Once the set is running and you release the start switch then terminal 27 is no longer powered and CR2 effectively prevents the power from the voltage regulator from going anywhere but to the exciter field.
I could be totally wrong here, as these prints are not like anything I've seen before in my 15 years of troubleshooting...but that's the way I understand them to operate anyway.
