Attempt to remove the entire tambour from the desk. If you cannot remove the tambour or if it breaks leaving part of the tambour inside the desk, you will need to disassemble the desk to retrieve it. If you are able to remove the whole tambour without disassembling the desk, proceed to step three.
To disassemble the desk you will need to either use your pliers or a small cat-paw or prybar to carefully remove the nails holding the top on. Once you have removed the top you will have a better idea of what you have to do to fully remove the tambour. You may only have to remove the top of the desk, but you may also have to disassemble the "cubby" section.
Clamp the slats that have to be replaced together using large wood clamps and position them so that they are face down.
Apply the glue lightly to the tambour, making sure that the glue does not drip between the slats.
Stretch the fabric and apply it gently to the glued tambour. Once it is in place, press the canvas firmly to help it adhere to the wood. Allow the glue plenty of time to dry.
Remove excess fabric from around the edges of the tambour with either scissors or a razor blade.
Put the tambour back into the desk and reassemble the desk.