Did mine on Monday....
And not to make Edd cringe but 91% works, too. It just takes a bit longer to dry. Unless you have Amazon Prime, this item is no longer available for free shipping. So I just go buy it at WalMart.
Okay, that is certainly true (and I most assuredly do
cringe), but let me explain my opposition to 91% alcohol.
1)
91% contains 900% (9X) more water than 99% alcohol. Water is a threat to damage your ProVari. Sure, the ProVari is engineered to resist it, but that doesn't mean we introduce water to the inside of our devices unnecessarily. The less water in the ProVari, the better.
2)
It (91%) is significantly more difficult to clean with, and will never get the contacts completely clean. This means that you are going to spend more time stabbing a Q-tip that has two things that can damage your version 2.5 ProVari in it. Isopropyl is a threat to the adhesives on the board of this model, so the less alcohol solution that you must put in the device, the better. No matter how careful you are with the Q-tip, some of the solution will get away from you. With 99% alcohol, one or two swabs with the Q-tip does the job.
3)
The cost is not prohibitive. Now if 99% alcohol was $25 a bottle, I would not harp on always using it. I have only needed to order it once. I ordered two bottles like the one on my blog, and they have lasted me nearly a year. I suspect these two bottles are a roughly 2-year supply...so the bottles cost $16 for both of them shipped. Is that cost really an issue? To me, using the best product for the job is an easy choice.
Now, in a pinch, there is nothing wrong with
temporarily using 91%. My only point is, if you are gonna keep a ProVari, you need to buy the basic materials that are needed for optimum maintenance!
EDIT: I added this to my blog, to really spell it out a bit clearer. So thank you for asking the question and challenging the assumption...I think my blog is better having this information in it!