I have not, but I did find an old thread with some tips and I've linked it below. I also don't know that any of the appliance stores would be very helpful, unless you're buying something else from them.

A good cleaning service may be another route to explore. HTH!

Here is a link that might be useful: Cleaning Old Viking

You don't need a pro for this. If the only problem is that it's dirty, then you can remedy that with some oven cleaner. If the stainless is scratched up, you can use emery cloth to polish it out. Then order some new knobs, and it will look brand new. However, you do NOT want to remove the seasoning off of the griddle or everything you cook on it will stick. And stainless itself can discolor from high heat and that discoloration can not be removed. It's part of cooking with high heat. So, there are things that can be remedied, and things that can't if you want a kitchen that cooks.

Post some pics for better feedback and information.

You can get a new Viking stainless griddle cover to put over the griddle when you aren't using it.
This will make it look "clean" all the time.

Thanks for the feedback - very helpful. I would definitely leave the griddle seasoned and surface intact. I more see that the whole cooktop looks kind of grimy to me. New knobs are a great idea, so is a griddle cover. There is a cutting board that fits over the griddle which I can have replaced. GreenDesign - thanks for your feedback on how to clean. I don't have a picture of the cooktop, but will get one once I get into the house (we just signed P&S today) and post. Chris thanks for the link to the old thread. I didn't see that one!