I'm pretty sure there's no tampering with the machines outside of the pre-tests, official draw, and post tests. Hell, they actually draw the balls up (5) times prior to an official draw so what's the purpose behind a post draw? If it doesn't happen within that many draws, it ain't gonna happen. Like you, I write 'em off as straight up because it just doesn't require all that to select (1) ball from (3) different containments...and they know it as well. My friends and I did a little experiment a while back which consisted of simply dropping a ball from three different cans, kinda like Pick 3, with no "pre-drops" involved. I had a theory based solely on dropping (1) ball (10) times to establish the following: repeatability, doubles, high/low percentages, all odd to all odd combo, all even to all even combo, and many, many more variances associated with Pick 3.
The results? Well, in my personal opinion and based on the data, the pre-tests have a very reasonable impact on even the above-average system (approach). See, in (10) draws, what is the possibilty of the same single digit being drawn twice? Just focus on (10) digits and (10) independent draws...no pre-draws. Now, the states conduct up to (5) pre-tests which causes at least (5) of those digits to already be "in circulation" while the other (5) are "reserves" so to speak. Now, what this means, to me at least, is that by the time the official draw is conducted 1/2 the numbers have already been selected in a single containment if there are no repeats.
So, either one of those digits will be drawn again from the same pool of pre-drawn (5), or, a "reserve" digit is drawn from the "reserve" pool of (5). Multiply this by (3) containments and you'll understand what the pre-tests really accomplish here. Don't try and cram all this in, okay. Let it just "ease" its' way in and holler back at me later with your thoughts.
L.L.