It looks like there are several different resistor values in my 500-C serial number 76944 receiver. R114 and R116 state in the 30001-49999 schematic to be 68K, but mine both read 53K on the multimeter. I'd ordinarily say that the resistors need to be replaced, but not when both read the same value. Too much of a coincidence. Another example is R113 and R115. Schematic reads 180K, but my two are 73K on a multimeter. I suppose it's possible that previous owners changed these resistors. I have no way of knowing. But since the last 500-C schematic I can find goes up to only 49999, that leaves out all the 50000-79999 serial numbered units. Anyone have insights? Thank you.