I believe many resistors in WPC games are Carbon based.
I expect / believe it's ok to replace these with metal oxide resistors. They tend to be smaller, have better tolerances, age better, and keep their resistance more consistently across temperatures.
So other than looking different, any concern with using metal oxide (assuming same rating) that I've missed?
FWIW, I 'm talking about WPC 1993 trough board 270 Ohm 2 watts.