Clay County uses the horrible ES&S iVotronic system for all of its votes at the polling place. The iVotronic is a touch-screen Direct Recording Electronic (DRE) device, offering no evidence, of any kind, that any vote has ever been recorded as per the voter's intent. If the allegations are correct here, there would likely have been no way to discover, via post-election examination of machines or election results, that votes had been manipulated on these machines.
ES&S is the largest distributor of voting systems in America and its iVotronic system --- which is well-documented to have lost and flipped votes on many occasions --- is likely the most widely-used DRE system in the nation. It's currently in use in some 419 jurisdictions in 18 states including Arkansas, Colorado, Florida, Indiana, Kansas, Kentucky, Missouri, Mississippi, North Carolina, New Jersey, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Wisconsin, and West Virginia.