Most of the replies to this thread presume that the "missing" machines would have to be tampered with and then returned to the ballot places in order to inject bogus votes into the election.
As a programmer, here's what I'd do...
1. Get my hands on one or more stolen machines.
2. Play with them as long as necessary to figure out exactly how they work, what safeguards they contain, and more importantly do *not* contain, and how the software in the machines is updated (no computerized piece of equipment these days is entirely *hardwired*, they all have ways to insert a floppy disk or whatever containing bug fixes, upgrades, adjustments for new data requirements, etc.)
3. *Then*, I'd just write a software "upgrade" for that model of machine (and test it well on my stolen machine) which could modify the behavior of *any* such voting machine in order to make it favor my candidate.
4. Now all I'd have to do is sneak the upgrade into one or more of the machines which are *not* stolen, and presumed "pristine" -- or *all* of them, if the election board is stupid enough to hook these machines up to phone lines for "automatic updates" or "automatic vote reporting".
"Hey, Harry, the manufacturer has a last-minute update for all the machines in this precinct, could you load it for me?"
Done right, the modified software would even self-destruct after the dirty deed had been done, and restore itself to be identical to the manufacturer's actual most recent release, at which point the machines would test as "untampered" no matter how closely they were inspected.
Yes.
Way too easy enough for a good (inside) operator to fake the electronic votes, then destroy the internal (programmed) evidence.
Method.
Motive.
Opportunity.
Add one more:
Concealment: The MSM REFUSES to aknowledge or report democrat vote fraud.