How best to eliminate LP warps


I own about 2500 LPs, and I like to think they're flat.  Furthermore, I espoused the view that warped LPs ought to be discarded.  But lately I have found 2 or 3 of my LPs that do have warps but sound too good and are too precious for the music recorded on them to throw away.  So I am in the market for ideas on how to remove warps.  I am aware that there was a device on the market that looked like a large waffle maker, to be used for warp removal.  I think Furutech made it, but I never see it advertised these days.  I am also aware of the DIY method of placing an LP between two glass plates and heating the ensemble.  The question there would be how hot and for how long?  Any suggestions are welcome, especially opinions on the efficacy of the Furutech.  Thanks.  Please no comments on vacuum hold down; I think it's a great idea but none of my five turntables has that feature.

lewm

@laoman , the AFI unit is a similar situation to the Furutech. My problem with the AFI is the silly stupid marketing on their web site. Temper PVC? You temper hardened metals to remove some of the brittleness. You can not harden and temper a plastic this way, utter BS. I personally won't tolerate that even if it was the best flattener out there. Furutech, as far as I have seen, does not feel the need to resort to this. To me this means their unit works so well they do not need to resort to misleading marketing. 

@terry9 , Peter Ledermann is absolutely right on that one but you can not adjust azimuth by ear. You adjust it by site which is easy to do. The best way to do it is with a mirror and a USB microscope but, I did it by naked eye for decades. The stylus has to sit symmetrically in the groove or you can accelerate both stylus and record wear. The message here is do not waste your money on a Fozgometer save and buy a USB microscope. For $300 you can get a really nice one.

@edcyn , I also share your enthusiasm for digital sources but for the majority of my life I have endeavored to improve LP playback and until I get to a point where little room for improvement is left I will continue to face the challenge. Digital is just digital, there is no challenge.  There is also no amazement. That a trench dragged along under a rock can sound as good as it does is amazing and as a collectable albums beat files by a long shot. IMHO the absolute best sound comes from properly mastered high res digital files. They are a 45 rpm record without the noise.

@mijostyn

"you can not adjust azimuth by ear. You adjust it by site which is easy to do."

Don’t agree. The Koetsu sits so low that even an approximate setting by sight is very difficult to impossible. In any case, sight is approximate to perhaps one degree, unless you have a microscope on a stand with crosshairs, which is registered precisely to the plane of the platter. Otherwise you are at the mercy of too many other variables, such as the construction of the tonearm wand - which is an absolute dealbreaker for me, as my wands are artisanal.

Speaking of USB microscopes, which ones do you find best? I looked a few years ago, and couldn’t find anything useful at less than thousands. A USB microscope would be useful to get me into the ballpark, and keep me there. A real timesaver.

Last, it is quite possible to adjust by ear. I use two tests: choral music in close harmony (Harmonia Mundi has lots of these; looking for ’sweetness’), and folk songs in dialect (looking for clarity of diction). But that’s harder to do without azimuth-on-the-fly.

If it's playable warp, don't eliminate it. If it's not playable warp, you can take risk of ironing it through cloth