K8077 IC insertion error in manual and unit has loud hum

Hi, I assembled the unit and performed the testing on page 22 of the manual. It passed through step 3. I then mounted the IC’s but the instructions say that IC1 is the TL074 but this can’t be correct because the TL074 is a 14 pin IC and socket IC1 is only 8 pins. I did my best and mounted everything, and the unit passed test steps 4-9 on page 22 and I adjusted RV3 to 10mv. However when I attached the speakers all I get is a loud 60hz hum once the power is applied and the switch turned to on. I double and triple checked every semiconductor. I double checked every single solder with a magnifying glass. Everything looks good.

Are the IC’s burned out (I did swap the 8 pin IC’s back and forth due to the confusion on page 22 of the manual)? Or is it something else? Help. Thanks.