Wow, I'm sure glad that I heeded everyone's advise and contacted Lowepro! I sent my pack in yesterday by UPS and I just received an E-mail from Lowepro saying that they were going to replace my pack with its replacement the Pro 400AM Trekker!
I can't say enough about this company. I have two of their packs for years and both have served me well. (They said that they replaced the zipper on the model I had with a heavier zipper before they discontinued the model.)
If you're in the market for a photo backpack, you can't go wrong with Lowpro!
Thomas