I've been asked twice by email this week "How do we clean AGA doors and Tunnels?" ( Tunnels are the shiny strip just inside the AGA oven) especially when they are encrusted with years of dirt/burnt on carbon. Well if they aren't that bad,say the AGA is a just a year or so old you can most of it off just with a wet microfibre cloth and some astonish solution. This will ensure that the shine on the tunnels will stay mostly intact; that is it will be still be mostly shiny. If it is it is thicker you can probably get the doors close to 100% with a soap pad so a Brillo pad. If you use Brillo on the tunnels be aware that if you really scrub the factory shine is going to dissappear forever. You can restore some of the shine with dry steel scourer but obviously isn't going to look like the factory finish. So it's your call. If the.doors are really thick we have been taking them apart and dipping the linings which does a great job. You just have to be careful when putting the door back together that you get the seals in the right place and you do up the screws tightly. For really encrusted tunnels I use a scraper with sharp blades and back scrape, followed by a soap pad.
We do most of our jobs cold and I would recommend that you do the same or do try and do the doors hot take them off and let them cool before you try and clean them or else you'll burn yourself.
The other alternative is to buy replacement door liners or tunnels. I have noticed that the replacement tunnels are infact stainless steel which will make them easier to clean.
Also the engineer from Spillers who fixed my own AGA last year says that people put foil on the inner doors tied on with brown string to keep them clean!