No, you don't need nylon screws.
When you say 5.0, I assume you mean the rotor measures 5.0 ohms.
When you turn the key on, you should have between +10 and +13 volts at the left ( outer) brush. If you measure 0 volts, then your voltage regulator is defective or its connector pins are corroded badly...............check for any broken wires.
If you still have the old mechanical regulator..................its time to replace with a NOS automotive solid state regulator..............big increase in reliability.