We are going to DIY install Pergo plank flooring over an existing linoleum floor. The linoleum is 27 years old. There are spots on the floor where the linoleum has been worn or torn, and the concrete subfloor shows through. We would like to avoid removing all the linoleum. What may I use to "patch" those bare spots and make them even with the rest of the old flooring? Also, we would like to install the new Pergo in the space beneath the oven (In the two houses I've owned, that part of the floor was left as bare concrete). What can I lay down to make that space even with the rest of the floor (plywood or scrap lineoleum, maybe)?