This is a just suggestion from experience, mine and others, regarding DIY repair of expensive lenses and bodies. Don't try to repair it yourself. It's just not worth the consequences.
If you have ever seen used lenses for sale in F condition, only usable as parts, there is a really strong chance that lens is an F lens because someone who didn't have the training or the manuals to repair it took it apart and at some point had that gut wrenching "oops, I can't fix it and now I can't put it back together" realization.
Most repair facilities aren't willing to take on the job of undoing the self inflicted damage done by the owner. The facilities I have used typically have stated policies saying words to the effect "if you take it apart and send us the pieces because you messed it up we will reseal the box and return it to you in the condition you sent it to us. We don't repair junk". In other words, if you take it apart wrong, it's just not practical time and cost wise to try to figure out what parts someone lost, broke, bent, tore, shorted out or put back in backwards.
On the other hand, if you sent your lens to an authorized repair facility today for a professional cleaning, there is a great chance that this problem will be fixed by a simple adjustment (as suggested by others here) that will be made routinely at no added cost to you while the lens is being reassembled. The lens will be opened and inspected. The problem will be obvious and it will be corrected. In most cases if you get the camera to them on Monday it can be back on your camera on Friday.
Paying a few hundred bucks to have expensive camera gear maintained is not a rip off. Spend the money if you have it. If you decide to roll the dice and repair it yourself and don't have the training and manuals it won't take much to turn it into a really cool looking paperweight or canoe anchor
Be careful.
Just as an FYI, I use Photo Tech and have nothing but exceptional results.
phototech.com
I hope everything works out well for you.