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

SO, who here that have excellent TT/arm/cartridge can actually say that when they play an average warped LP that they can actually HEAR manifestations of the warp?

@jw944ts, having vacuum clamping, minor warps are not a problem for me. The warps I need to flatten are the major ones and they are easy to hear. Many arms will be airborne off these warps. The Schroder will track just about anything and once you are use to extreme pitch stability these warps become obvious. Minor warping may not be so obvious. My problem is that when the warps get bad enough the vacuum can not grab a seal.

@mijostyn , though I have many LPs and many have some  minor degree of warping, I honestly have never heard an obvious audible effect....perhaps I am not a good listener, or it just that the areas of warpage have never coincided with a musical passage that would make the pitch variation apparent...and i have never had a LP whose warp was SO extreme that it caused skipping or mistracking....just my experience

@jw944ts , you haven't lived until you've seen your tonearm take off:-)  Any warp that can be easily seen without the record spinning will cause a noticeable pitch change if you are use to digitally stable pitch on record playback. It appears to me that given smaller warps and eccentric spindle holes we are use to a certain degree of pitch variation and our brains ignore it. If you are use to really stable pitch the irregularities become, I would not say obvious but certainly noticeable. A couple of months ago I was listening to Polini play Chopin and the piano was wavering. Sure enough the spindle hole was way off, a DGG pressing. 

@mijostyn

Interesting observation about eccentric spindle hole placement: how did you measure this to confirm the degree of displacement off center?

(BTW, while DGG may have misplaced their spindle hole, RCA LP's are just really bad!)

Thanks.