Flattening Aluminum Oxide Stone

So... asked to see someone's spare kitchen tools in storage. The box contained nothing I really wanted, all I got was a spare meat fork (enrolled in culinary program and need to fill the knife roll). Lo and behold there it was: a stained carbon steel 9.5 inch chef knife. If there was ever a logo on it it is long gone. Handle made of nice wood, stamped triple-riveted standard classic carbon steel knife. Of course it was dull and impacted.

Took it to my cheap aluminum oxide stone (india stone) which is 8"x2" and ground off the messy edge, establishing a mostly new secondary bevel. I like working the edge from death so I can easily appraise the metals quality and hardness. Flipped the india stone over and it honed up quickly to the higher grit, then finished it on a DMT 6"x2" extra fine diamond tablet for a screaming (by cutlery standards) edge. Wow, carbon steels take a very nice edge quickly, no wonder I shave with them.

The coarse side of my india stone has dipped a little, and isn't entirely flat by width, either. I own and use some Calphalon aluminum cookware, which i understand is aluminum oxide, too. It get soft at higher temperatures... since I don't want to wear off any more diamonds from my diamond tablets... or wear into my (albeit not flat) Norton flattening stone (silicon carbide) I am thinking of heating the india stone in the oven and then cautiously lapping it with the Norton flattening stone.

Does anyone have experience with lapping cheap india sharpening stones? Would it be a good idea to heat in the oven and then work on it with the Norton flattening stone? I don't want to use my DMT extra-fine tablet or even my DMT coarse 8"x3" tablet, because the coarse is dedicated to being the real lapper for my razor hones and the extra-fine tablet is great for... quickly putting a screamin' edge on my cutlery and rounding the corners of the hones.

What do you guys think? To flatten or not to flatten? What temperature? I cook with the aluminum oxide but I'm thinking intentionally lapping is different from cognizance of softening at higher temperatures. I don't want to buy another india stone, despite their price. I want to use my current one for life. (I often hone other people's cutlery, it's fun to bring 'em back from the dead and watch people's eyes light up with surprise and delight!)

For the record, I still enjoy free-hand honing of cutlery more than razors, though ultimately using the str8s is more rewarding in the long run. TIA for any advice that comes my/our way.

I don't know about cooking the stone. I would suggest some 120 grit wet & dry sandpaper on a tile or a countertop for starters and follow with some 325. If you use the Norton flattening stone IMO you'll ruin it or at least damage it to the point where it will need flattening.

Maybe some of the cheap sandpaper. I thought softening it would be a good idea. My idea was that silicon carbide was harder than aluminum oxide, especially if the india stone was hot. I don't want to have to spend more money on sandpaper. On a related note, I've found a cheap source for my "honer's crack." I don't even have to invest the 1.29 per sheet for wet/dry sandpaper for ripping of lots of steel during the bevel setting of eBay razors. The hard steel of a str8 wears off the abrasive sandpaper so fast I can get away with using regular (220 grit) sandpaper and there is no issue with tearing of the paper, it's used up before the paper weakens.

"If you use the Norton flattening stone IMO you'll ruin it or at least damage it to the point where it will need flattening."

The Norton flattening stone already isn't flat. It came slightly warped, length-wise. I used it on my Nortons in the beginning of my honing adventure and found, to my dismay and frustration, that is it a bad flattening stone. Also, of my two combination stones the 4k side is evil. It is unsalvageable as a quality hone. Just ask RandyDance, he's got solid reputation. I took it to his place and he worked on it with sandpaper, we tested it, still bad. Then took it to a belt sander to wear off a LOT of material, still bad. That 4k Mexicano Norton is evil. Two combination stones (220/1,000 & 4,000/8,000) and a flattening stone and only the 220, 1,000, 8,000 and prep stone work as designed. 66% success rate. The flattening stone is not good enough. I can use the convex side to correct the irregularity of the wear on the coarse india stone. Trust me, it's not like I don't have enough time to ponder these things...

P.S. the carbon chef knife is great. Have to put it through a real kitchen work-out to gauge its true worth but it's nice.