IIRC, the PHY on most FireWire devices is usually a separate piece of silicon, but I haven't dismantled a FIREPOD to see if they did it that way or not. I'd expect it to use something like an FW802b. Look for a surface mount chip with a crapload of pins near the FireWire connector that's made by a FireWire chipset vendor like TI, Lucent/Agere, LSI, or NEC.
Before I went to the trouble of replacing a PHY, though, I'd check everything else—fuses, internal connectors, solder joints on the FireWire connector, cracked traces on the board, etc. Unsoldering a PHY is the sort of thing that even somebody with a lot of soldering experience will probably have a hard time doing, simply because they tend to come in 64-pin surface mount packages....
Before I went to the trouble of replacing a PHY, though, I'd check everything else—fuses, internal connectors, solder joints on the FireWire connector, cracked traces on the board, etc. Unsoldering a PHY is the sort of thing that even somebody with a lot of soldering experience will probably have a hard time doing, simply because they tend to come in 64-pin surface mount packages....