Make certain you have read the 3M 1720 Overhead Projector manual thoroughly before attempting the 3M 1720 Overhead Projector bulb replacement on your 3M 1720 Overhead Projector. Without touching the surface of the 3M 1720 Overhead Projector lens, remove the lens tube and set it aside. Write down the number from inside the tube's inner lip for the purpose of make, model or serial number for any future need to buy 3M 1720 Overhead Projector replacement parts. Your bulb should be sitting just beyond the opening of the 3M 1720 Overhead Projector body. Reach in with two fingers and disconnect the 3M 1720 Overhead Projector bulb. Reverse these steps to re-assemble your 3M 1720 Overhead Projector. This concludes the 3M 1720 Overhead Projector review - be sure to read the entire 3M 1720 Overhead Projector manual.