Does those two resistors look original in regards to installation?? Physically, to me they look like the original resistors of that time period. If they are original, they must have worked properly as one time. I would look elsewhere for the problem of birding-whistling. Are any of the tube shields missing?? A bad AVC Capacitor or a problem with parallel wiring can sometimes cause the same problems. Even a micro-phonic vacuum tube. Tap the tubes lightly to see if there are any changes in the sound.
Ralph
