The trap was to shunt to ground any strong stations that were near the set's IF frequency. When the set was built, there were powerful coastal code stations down below the broadcast band that could leak into the IF. They aren't there any more, so an ordinary .02 or thereabouts cap will do.
Edit: well, maybe not exactly. If the trap were in the RF circuits it would be for the shore stations. If you have a trap there, it is superfluous today; they often have trimmers to be set to the IF frequency. With the Philco trap on the radio in question, consider the following:
http://www.philcorepairbench.com/tips/svctip37.htm