@TheMythOfSisyphus Honestly I couldn't tell you. It seems like some vinyl (it was coloured) just has a really low melting point. I had it on the second lowest time setting, it was correct for the weight of the vinyl. But it created a hard jog to the left that although my needle can track it, there's no way I'm gunna play it like that.
But it was very very warped so perhaps it was just that when flattened from it's warped state, the grooves just have to jog left. I'm not sure that it's actually melted so much as stretched from curved to flat.
I think if the warp is severe it's not going to flatten properly. It may be flat, but like you said, I think the groves are going to shift. These flattening machines aren't miracle workers, they have limitations.
It was a PIF from a year back from @EmeryRK I believe, and horrifically it was The Mars Volta Noctourniquet... BUT is was very warped and almost unplayable so it kinda had to be done... but man it sucks that it's toast... Now I just gotta go buy them all...
Honestly I think it's a combination of the warps being pretty major league ones and also the vinyl I think was done privately by Volta and I have no idea what plant pressed it and whether they use good quality vinyl...
But it seems like certain really steep warps just don't flatten properly, I think they just stretch slightly and that causes the groove to jump over enough to look like it's taking a right angle turn...
It's actually happened twice before and every time it's been a record that was warped post pressing, like in transit or on someone's shelf, I've never had an issue with anything that came "naturally" warped... So that may have something to do with it. The way the Voltage were both warped the same way makes me think it was after it was pressed that it happened...