Warped records, can they be somewhat dewarped?

A record clamp can help with many warps. One of the newer perimeter clamps can help with what's left. Between those two clamping systems, they will iron out nearly any warp that is under consideration for being played. The perimeter clamps are not cheap, some costing about $500.

There's a guy on AA who offers a periphery clamp custom made to fit your platter. I don't know his costs or details, but here's a link:

http://www.audioasylum.com/audio/vinyl/messages/199121.html

Some people I have read about put the record (leave inside the jacket) between two flat heavy objects, such as books and leave them there for a month or so. Others take this a step further and put them in an oven on the lowest possible temperature. I think that may be risky for a number of reasons. Of course you should try this on records you don't care that much about at first. I've tried the books without oven and it seems to help a little. I am thinking about trying this, but put them in my attic which is warm, but will not get near flammable temperatures. Also what this does to the grooves may not be good for the sound. Try this at your own risk. I will accept no responsibility in this area, only something to think about. :')

Finsfan, I can provide you with a method that works like a charm. Although it's a little extensive, you will absolutely have a FLAT record when you're done. I have a 2" thick maple chopping block in my kitchen. I also own a piece of granite that I, at one time, used for a turntable base. It weighs about 40 lbs. The procedure is as follows:

I put the granite slab in the oven @ 175 degrees for approx. 1 hour. I place the warped record in a rice sleeve, on the chopping block with a piece of "oaktag" paper on each side of the record, (in it's sleeve). I place the preheated granite on top of the record and allow it to return to room temperature (usually overnight).

I have used this process on records that were significantly warped. Every time, they come out dead flat. If you own the above mentioned items, it's a really easy and extremely effective method. If you have an extremely warped record, it may return to a flat condition, but the grooves may have suffered from a loss of concentricity, and possibly may now be physically distorted. Then you're screwed.

Best of luck!