I have a Great Lakes hot tub, 1997 vintage but in good condition. I saw it run before I bought it and now that I have it home and hooked up the ground fault breaker is tripping. If I put a regular breaker in it runs fine and everything works. Tewsting it, when I unplug the Transformer from the circuit board the ground fault breaker is good and does not trip but to say the least once the transformer is removed the control panle does not work. Is it possible a bad transformer ios the root cause of the groiund fault breaker tripping?

Yes, the transformer can be defective and causing the GFI to trip.