Paul,
R471 is 4700 ohms and R675 is 4300 ohms. These are connected to the cathodes of the tunnel diodes. The schematic I used shows the Nuvistors. I do have one that has the FETs instead of the Nuvistors. See if yours has these resistors. Each resistor goes through a 47 ohm to the base of the transistors. The schematic for higher numbers was helpful from Michael. I will keep a copy of that for mine. Since your resistors you mentioned, 300 ohms, are close to the limit of tolerance, you can change them if you want. My post was not intended to confuse anyone. Apologies to anyone I confused.
Conversion to FET from Nuvistor I had a post about a couple of months ago. I did this in a 454. The same thing can be done in a 453.
The 5642 rectifiers can be replaced with a 2CL2H or 2CL2J.
Mark
