Equasonne radios contain only about 6 to 8 resistors. Many of them tend to drift, or open as they age. As there are so few of them, it is not a big task to test them all, and replace any that are broken, or substantially out of specifications. Replacements should be as close to the original values as possible (say within 10%), and of a wattage rating that at least meets that of the original. More than one resistor can be combined in series to create a value which cannot be obtained in a single resistor. There is no harm in replacing a resistor with one of equal resistance but higher wattage than the original, as long as it will physically fit into the radio. Higher wattage resistors are generally bigger. Higher wattage resistors are generally uglier too!
Other than that, resistors are resistors, and they can be purchased from any electronics shop. Antique Electronic Supply sells suitable resistors, as does Radioshack.com. A small local electronic shop might not have appropriate values of the larger wattage resistors in stock, and may have to special order them for you.
Click the following link to view a Sparton Resistor color code chart.
(1) A package of the ubiquitous 1/4 watt carbon resistor, in this case purchased from Radioshack. These resistors will be of no use to you in a Sparton radio, as the lowest rated resistor found in an Equasonne is 1/2 watt, and most are rated much higher.
(2) A Sparton A-3397 1,000 ohm 2 watt resistor from an Equasonne radio.
(3) A Sparton A-2934 20,000 ohm 2 watt resistor from an Equasonne radio.
(4) A relatively modern 2 watt carbon resistor utilizing the standard modern resistor color code.
(5) An old wire wound power resistor (exact wattage unknown, probably lots).
(6) A modern ceramic 5 watt power resistor.
(7) A modern ceramic 10 watt power resistor.