If the cartridge was an OEM Tetrad the color on the socket
indicates the output. Tetrads were known to go int often. We
kept all the colors in stock.
You could also try the AUX in or tape in & see how it sounds.
Also the phono in #1 & #2 should both be for magnetic cartridges
with a switch for ceramic on one of them IMHO.
73 Zeno
LFOD !