What is the jackpot threshold where they are required to crack open the machine and verify there are no errors? I'm guessing $100,000?
Let’s put it this way, I have never seen it done on a machine for a jackpot smaller than $100,000. Not like I have won one, but I have seen it done. I have won $20,000 twice and it was just paid out as if it were $1200. I’m guessing it varies by property. I have seen people win $200-400,000 on VP at Wynn and they didn’t rip the machine apart.
It seems like slot jackpots are sometimes "verified" if the Grand/Maximum jackpot is hit, regardless of amount. Since I'm not a slot player I have no direct experience with this, only observation of seeing others hit such jackpots.
I don't know the regulations, which probably vary by jurisdiction. But I personally triggered a versification after I won $20K royal and it was one of many (5 or 6? by me) in less than a week, certainly over-royaled. That machine was surely losing money in that period, so they need to verify.
I would love to chat with a slot tech and understand what they are actually doing when this happens. Just making sure nothing weird is plugged in inside the machine and looking at the play history? What else is there they could actually do? ...I'll work on winning more five and six figure jackpots so I can ask - will report back shortly.
How about this possibility? There is no Nevada gaming rule regarding mandatory verification of slot machines when reaching a certain jackpot level, and instead it's up to each casino on when to do this, as they have a right to protect itself from customers who might compromise their machines, or from a machine malfunction. I'll throw in that for the wide area progressives (multi property) the company running the progressive (IGT for example) probably has a say in requiring casinos to verify the machine in jackpot payouts that they administer. I did a basic search in the Nevada Gaming rules, and see nothing on this topic.
In Missouri at least, they have to verify the critical storage program media at $50,000+. I've never seen state requirements in Nevada.