If one can get a hold of the code, figure it out and find a way to load it back into a machine then anything is possible. It does require a certain set of skills that Singer does not possess.
Of course, if you could do this with a casinos machines you wouldn't bother with the RNG, you would just program in certain sequences that would produce winning results as was the case with the NGC employee Harris. Believe it or not the manufacturers have things like check-sums and seals to make this much more difficult. They are just as cynical as you are
Yes, there are tests for randomness. And, the machines are tested by the various gaming commissions.