Remove the standoffs and screws from the stock tube pcb and install the standoffs on the new tube PCB board with the fat mounting side on the tube socket side of the new pcb

Solder the new sockets to the PCB. Make sure you're installing them on the correct side!

When mounting the new tube board back in the chassis leave the nut off of the stand off back between V2 and V3. Tye teeth can short the tube PCB. See photo.