Palm Beach County’s elections supervisor, Susan Bucher, said that her county’s machines are too old to conduct three full recounts as quickly as required, and the county would be unable to meet the deadline on Thursday.

Florida’s protracted 2018 midterm election has revealed the warts of an imperfect voting system that normally go unnoticed. This time, the world is watching, and South Florida election officials are being exposed for sloppy processes that in some cases, a judge found this week, violated both state law and the Constitution.

Yet those very procedures are common during elections, political analysts in Florida say; they just don’t get much attention most of the time because most elections end with wide enough margins of victory that few people scrutinize them.

Repeated claims of mismanagement and worse by Mr. Scott and Mr. Rubio have drawn a backlash from Democrats, who said the governor’s order to law enforcement to impound voting machines was inappropriate.

“In suing to seize ballots and impound voting machines, Rick Scott is doing his best to impersonate Latin American dictators who have overthrown Democracies in Venezuela and Cuba,” Juan Peñalosa, the state Democratic Party director, said in a statement. “The governor is using his position to consolidate power by cutting at the very core of our democracy.”

But some number of irregularities do appear to have occurred.

On Sunday, one candidate filed an affidavit in court from a fired poll worker who claimed to have witnessed elections employees filling out ballots days before the 2016 election. It was unclear whether what the worker witnessed was wrongdoing, or a routine process in which staffers fill out fresh blank ballots to replace those that come in too bent, torn or otherwise defective to be read by machine. The affidavit was intended to prove that similar problems could be at work in the current election.

In Broward County, 22 rejected ballots were mixed in with about 180 valid ones and were counted. In Palm Beach County, damaged ballots that were duplicated by hand, as required under state law, were handled without independent observers having a good vantage point to witness the process. Staff members had made rulings themselves on questionable ballots that were supposed to be judged by a three-person panel.