not much you can do but wait. 83 is low, but I also think if it was a fairly steady 83, they should hatch and you should have big healthy hatchlings. I know breeders who incubated at low temps with great results. your temps are slightly lower than what they incubated at. I wouldn't change the temps any. vpi and the breeder who incubated at lower temps has also change temps durning incubation with another clutch, both reported bad results.