The voting machines have been rigged ever since they started being used. That's the primary reason that they were so quickly put into service by all the right-wing ideologues during the GWB years.
There are a very large number of studies that have been done and continue to be done that have established the "red tilt." It's about 3% Repub tilt throughout the country, larger in some places, usually in states where Repub leaders have already cheated their way into office or have control over just about every facet of the voting process (like KS where it's about 7%).
The best and maybe the only chance that Trump has, assuming other things don't happen that hurt Hillary, is for the vote to be rigged in key states where the pre-election polling indicates smaller differences between the candidates. The tilt will happen regardless, but maybe Hillary will continue increasing her lead so much that any all-out effort to steal the election will be deferred by the far right-wing owners of the voting machines out of fear that Dems will for once could discover enough guts to demand that the vote be audited or recounted where the results are questionable.