Here is the process:
To clean the enamel kettle. I first cleaned it with a degreaser (Mr. Clean) and warm water, followed by wiping it down again with plain water . For those "baked on spots" I used a ScotchBrite pad and on really nasty stuff I lightly used a wire brush in a very cautious fashion. I did not use a wire brush on the aluminum pieces.
To clean the vents I first tried a polish. It didn't dent the caked on ash that had mixed with water at some point and turned that ash to concrete on the 3 bottom vents. I tried a wire brush but was afraid it was too aggressive and it would be too easy to miss small spots. To my horror I ended up sanding the vents with 220 grit sandpaper. It worked the best out of anything and cleaned them up in a short amount of time. Doing this DID scratch the aluminum but since they are on the bottom I could live with that. I posted photos earlier in the process showing the vents before and after if you are interested in seeing those. After sanding the vents I then used aluminum polish on them to make them shine a bit. The lid vent need nothing more than the polish and a great deal of elbow grease.
I made any needed repairs to the kettle. There were some bent edges on the lid that needed fixed. I then sanded any of the rust spots. I tried 220 grit sandpaper and it was too big and bulky for 95% of the spots that I was trying to sand. I tried 0000 steel wool but found it very labor intensive. Finally I ended up using a toothbrush size wire brush that I have had for years. The bristles weren't soft but certainly not stiff. Definitely softer than the run of the mill hardware store wire brush. This worked great. The bristles could reach down in the spots that were pitted but the bristles didn't scratch the enamel on the kettle. Next up was the masking tape. I believe it was swamprb on here that said you need a chitload of masking tape. I am here to tell you that a chitload equals one full roll of 1" wide roll of 3M masking tape that is 60 yards long. I masked anything that wasn't getting painted. When I came to some areas that had say 8 small spots of rust all clustered together I masked around the group and painted with Rustoleum Engine Enamel good to 500 degrees. I wanted to use the Rustoleum High Temperature Paint since that is good to 1200 degrees but that only comes in flat black. Next time I will take a small artists brush and spray in to a small cup and dab the paint in to those tiny spots. Those "groups" of spots now show a difference in shine compared to the enamel so I think the artists brush is the key on the small spots. Larger spots, well they are what they are, tape around them as close as possible and do the best you can. Once you remove the tape (I waited 2 days) I used 0000 steel wool to blend the transition from paint to enamel. Only sand that immediate edge, not across the entire painted surface since the steel wool will take the gloss finish off the painted area making it stand out from the enamel even more. Next up I cleaned the entire kettle again to get any foreign substance off. Then came the application of the polish... which was WD-40. I (carefully) sprayed a little on at a time and rubbed it in with a paper towel. I applied WD-40 to the entire OUTSIDE of the kettle a total of three times. Each time I would spray, wipe off any excess, let it sit for about two hours and then lightly wipe it down again. After the final application I let it sit overnight and then wiped it down and buffed it by hand with a clean cloth.
Next in the process was to make any repairs to the wood handles. I sanded the pieces using 220 grit sandpaper being very careful to not change the shape of them (photos posted earlier in the process). With the wood so dry removing large volumes of handle in each pass of the 220 was easy so be sure to take your time. A little wood putty on cracked wood on the underside of the handles, a little in the slightly stripped out screw holes and the handles were ready to be finished. I experimented on the backs of the handles with lemon oil, teak oil, a leftover oak stain and some leftover satin polyurethane. The poly gave me the color I liked so I put on three coats with a light sanding before applying a new coat.
All of the hardware was replaced with stainless.
I bought two major pieces for this grill. One was the cooking grate. I replaced the rusted one with a new Weber grate with hinged sides. The old charcoal grate I kept and used after a wire brush attached to my drill had a good long go at it. The second purchased piece was the Weber kit for the entire bottom structure. Below the kettle is all new. It was about $27 with shipping and after having the kettle come out nice I knew I had to spend the money. I am so glad I did, it was worth the money spent. All told I spent $50 but the fun I had researching and restoring this grill was well; priceless. The real fun will be this Sunday when I toss some lump in the starter and cook some fresh corn on the cob (without the husks & later sprinkled with chili powder and a wedge of lime squeezed over top) and some Mexican Spiced rubbed ribeyes that will be topped with a disk of lime butter while resting.