ply woes.

I'm going to guess that your windows may still be leaking.

I'd not blame the ply, something is causing it to delaminate.

What was replaced? The sashes? Where was it leaking? Has it been properly fixed and sealed? Or do you have excessive humidity and condensation?

Much as I like shellac for a finish, it would not be my first choice for windows. It can be affected by water more than poly, but I doubt it is your root cause.

I think I would call Pella and ask them what's up with their plywood. Seems they are only good for 2 1/2 years, not a resounding recommendation for Pella :)

Is the face veneer up enough so you can lift it enough to see under it? Stained under (from water)?

No they replaced the entire window again. This time they built it in the shop and mounted it. The previous time it was built on site, and they did not caulk properly.

No, they are all just puckering at this point.

Pella ain't what it used to be - - - but then again they now have more than one grade. The "dealers" get one grade,(or possibly more) the "big boxes" get only the lower grade.

These were bought directly from the dealer.

Understood but moisture seems to be the problem "again".

After having worked for 2 window installation companies my bet is still on a screwed up installation.