My rolltop's tambour would not open all the way. It was like it was jammed from being able to be pushed up all the way to the top, in the totally open position. This meant the drawers were locked. Fortunately, not all of the drawers were shut.
These instructions will enable you to get your tambour all the way open and unlock the remaining drawers, provided you have the same scenario as I did.
To release it I had to simply unbend the piece of plastic and lift the drawer vertically thus allowing the plastic piece to slide back through the slot.
In my desk, it comprises a vertical wooden shaft with cut-outs to engage the locking hook on the back of each drawer.
In my particular case, there is a plastic tube that fits in a hole on the underneath side of the desktop. This plastic tube is the mechanism that moves up and down as the tambour is lifted and lowered. This plastic tube is open at one end and has a flat rectangle at the other end. The open end fits in a hole and a flat rectangle is the part that actually moves the pivoting wooden lift.
The rectangle piece got caught on some wood and would not move. This prevented the tambour from completely opening. I simply took a long tool, reached in through opening left by the removed drawer and unjammed it. The tambour was freed up to work properly!
In order to keep the drawers from locking again if the tambour gets jammed, I removed all the drawers and unscrewed the metal hooks. These hooks are actually what is inserted into the wooden shafts cutouts to lock them in place. They are located the back of the drawer and easy to remove with a screwdriver.
