An algorithm that determines just one more series of vibrations will increase the likelihood of the seven, not guarantee it. Perhaps it can be adjusted to where the occurrence of 7s appearing is slightly increased.
For example the plate that vibrates the dice.
What I mean is, I could easily imagine those machines being adjustable to the whims of the casino. But I honestly wouldn't be surprised if the truth was somewhere in-between.
It's hard to claim it's rigged on a game that's already in the house's favor.
