Wicked Winnings 2

Earlier this evening I was at my local Harrah's and was playing a WW2 machine when a slot tech came by and started doing something to the other WW2 machine next to me.
I'm always interested in watching what they are doing so even though I was playing the machine I watched what was going on while not trying to be too obvious.
He was on a screen that said Average Weighted Payback Options and it had five sets of numbers on it with % signs after them. The lowest was 87.3% and the highest was 94.3%, the other three were in the middle but I can't recall exactly what they were. I know that casinos order machines with several set payback options on them so this makes sense. I also noticed that it said below which of the percentages that particular machine was set to- and it was the lowest option (I looked at that again to be sure).
I don't think he was changing the payback percentage or anything, looked like he was doing a test or something, but was interesting to know how low or high WW2 can be set at.
It also partially confirmed the rumor I heard about that particular Harrah's that they set all of their slots at the lowest % (I seem to lose more there than at any other local casino).