Chances are there is more damage than the visibly burned part. This are especially JFETs (SOT23) controled by that comparator, but also the LTC1050 and another OP amp at the input.
The good thing is that the LM339 is readily available and the chip itself not critical with leakage or fast signals.
The burned PCB remains can be somewhat conductive. So one would need to remove it and maybe patch the hole to put in a new part with more flying lead connections. Alternatively one may just isolate the area and have the replacement in dead bug style.
It may be worth forst checking the suspect parts near by, as one may want wires directly to these parts.