I removed the liftout yesterday for the purpose of screwing some masonite siding to it, to keep engines and rolling stock from falling to the floor should they ever derail. When I reinserted the section today I found out that the track did not align correctly at one end. Bad luck! Easy and repeated track alignment was supposed to be the hallmark of the design in the first place.
After having stared at the misaligned track for some time I came to the conclusion that the trouble was the cork sub roadbed. The tracks make a tight curve before entering the liftout so there is quite a lot of stress on the cork, from the curved flex track. Nothing had broken loose but my guess is that the soft cork has been deformed making the tracks misalign. Not very much, but enough to make cars derail (good for me that the new siding was in place).
The cure is to lift the track closest to the layout edge, remove a slice of cork (about an inch or so) and insert a piece of plywood instead (along the layout edge). The plywood will be rigid enough to prevent the track from ever shifting again. I hope.
The other day I mentioned some drawbacks (in my opinion that is) of using PCB ties. One issue was that it is hard to get a color match with the rest of the ties. Not everyone agreed that this is a problem. On the prototype not all ties are the same color and if you place your PCB ties somewhat randomly the track will not get a stripy appearance. Good point!