The crystal that drifts the most in that radio would be the PLL offset crystal. This is the one connected to the clarifier control. Pretty sure the frequency is 14.01 MHz in that model. One way to be sure is to tune in the crystal's output carrier with a ham or shortwave receiver that's fairly stable. Tune it in on sideband and you'll hear the drift that way.
An old buddy came up with a cure for his Saturn. He powered a 5-Volt 1-Amp regulator chip on the unregulated side of the power supply. The power switch doesn't shut off this side of the power supply, only the regulated side. This fed power to a device called a PTC thermistor. It had been salvaged from a deceased 8mm camcorder. Its job in the camcorder had been to prevent the tape-head drum from getting cold enough for humidity to condense on its surfaces. Since the device has a higher resistance as the temperature goes up, it will get warm until it reaches an equilibrium temperature and acts like a built-in thermostat. He clamped it to the side of the PLL offset crystal in his radio. The power to the thermistor was always on, so as the radio warmed up inside after it was turned on, it reduced its heat output to keep the crystal at the same temperature.
Rick never shared any before-and-after measurements, but it did make the radio a lot easier to use.
73
