i have some red birch veneer which is peeling off the sides of some bookshelves. Most locations are small “bubbles” appearing at the edge of the face of the vertical sides. In one case the veneer is about 1/2 off of a side. In all cases the veneer had been aplied over the face of plywood. I tried heating it with an iron, pressing it in place, and then clamping overnight. That worked for a while but 2 weeks later it started peeling again. Any suggestions?