I have an Icom IC-28A I picked up cheap, with a warning that it only
worked on receive. Sure enough, the receiver works brilliantly but
there's almost no power output on transmit. (The needle on my power
meter moves, but almost imperceptibly; we're talking milliwatts here.)

The damage wasn't hard to spot. Q17 has overheated so badly the case is
charred and cracked. C54 is burned beyond recognition, with a matching
smoke spot on the inside of the top cover.

The schematic shows Q17 as a 2SA1359 PNP transistor. The emitter is
connected directly to the 13.5 volt power input, right after the
reverse-polarity protection diode. C54 is between the collector of Q17
and ground. I'm leaning toward the theory that C54 shorted and caused
excessive current in Q17, but I don't know these radios well enough to
know if that makes sense, or if I'm seeing the results of a more serious
failure elsewhere (like a bad PA module.) It's a bit hard to suss out
what Q17 does precisely because no pinout is provided for the PA module.
Anyone have more experience with this rig?