The unswitched outlet in the back should have ~120 volts "AC" regardless of the switch condition or position.
Remember were reading a.c. voltage on the primary side. You should also have ~120 from your dim bulb tester.
If these conditions aren't met, there's no point in checking anything else. 61vac isn't even enough to close the relay.
If you're powering this on at all it needs to be through a proper working DBT and for no longer than it takes to get a stable reading assuming your leads are hooked up to the test points before applying power. Once you get a stable reading immediately power off or you are causing far more damage to the unit.
Leave the unit off. Let's test your DBT. A 60-100 watt bulb works fine. Plug it in and plug your leads into the outlet. With the meter set to read a range of 120VAC, turn it on. Are you getting 117-125 volts?
The light bulb is in circuit to limit current, not voltage and to alert you by glowing brightly If something inside the unit is drawing excess current which is what is making more current through the bulb making it get brighter. AFTER letting it sit for a while, then plugging in through the dbt and turning in, it should glow brightly right away and fade out. This is current filling the main filter capacitors which only takes a second or two. It usually helps to dim the lights and shut the blinds while doing this so you can see this process better.
So, 120 or so from the DBT without the Marantz plugged in?
If yes, pull the output transistors and test them outside of the unit. It's only 2 screws each. Do one at a time so you don't mix them up.
Here's a link to how to test them properly.
http://audiokarma.org/forums/index.php?threads/bipolar-junction-transistor-testing-basics.43186/
Do this before applying any more power to the unit.