Zenith Tube Amplifier- tubes don't light?

[Magnavox300]

Just bought this Zenith 5L29 amp from Ebay to power a Cobramatic turntable with a ceramic cartridge.
I Plugged it in today, but no response!
The person I bought it from said it needed a pre amp to power up.
I figured since it had a power transformer, it did not need one, that it was integrated.

I looked at the schematic, and there is a tuner power socket plug in the back,
that needs to be plugged in from the tuner, or (pre amp,) that originally came with this to complete the circuit.
So, can I simply bypass that tuner power socket, and connect the wires in that area together to complete the circuit?
Will that give me power?
Thanks for any help!!

Magnavox300