Your G1 voltage is way too negative which biased off the picture tube. I would trace the circuit down and check the parts. There is usually some way to feed a variable positive adjustment voltage into the G1 circuit. This may be defective.
I would expect the G1 to be about -40 to -60 volts in normal operation. Try connecting a variable resistor box to the G1 pin on the neck board and ground. Then starting at the highest resistance, slowly reduce the resistance and see if the picture comes back when you reduce the G1 voltage.
The G2 voltage seems low. This is an high-impedence circuit and your meter may be loading it down. I use an 100 to 1 probe on my meter when I check G2. I would expect 300 to 450 volts.
Video cathode voltages also seem low. I would expect 50 to 70 volts here. Is your B+ voltage to the CRT neck board OK ?
Hope this helps. John