Can you see the Spark Gap Arc? Yes

a. Check the PA Cable to the Torch.
b. Check the Hi Freq, Transformer.
c. Check the capacitor that couples the HF to the Hi Freq Transformer.

Can you see the Spark Gap Arc? No

a. Check the voltage to the primary of the high voltage Transformer
b. check the output to the high voltage Transformer.

Do you have any arc at the torch? No

a. Check to see if you have open circuit voltage from the power supply
b. Check to see if you have proper start gas flow.
c. Make sure the air line connected to the torch is free of all moisture.
d. Make sure you torch is not dripping or leaking any water.
e. Make sure you have good consumables in the torch.
f.  Is your plate/sheet of metal making good contact to the table for grounding purposes.