Replacing a rear-projection TV lenticular screen requires opening the TV set, removing the front bezel, sealing tape and old lenticular screen, taping the new screen in place, then closing and testing the TV. Although the repair is not difficult, consider total repair cost, including your time, versus the price of a new TV. The last company to make rear-projection TVs, Mitsubishi, stopped manufacturing them in 2012, so parts for this older technology can be hard to find.
To start, check the make and model number of the TV, then locate parts and repair information online to verify that the repair is something you want to do and whether there is a separate part number for the lenticular screen. Locate a replacement screen for sale. Verify that you have the correct size and type of screwdriver and mounting tape, if needed. Prepare a clean work area to avoid getting dust in the screen. Also, be careful to avoid electric shock, as the internal parts of TVs store electricity even when unplugged.
Open the TV and remove the front bezel around the screen. Check the repair manual for specific instructions, as screw locations and bezels differ among manufacturers. Once the TV is open, locate the lenticular screen between a protective screen at the front and a Fresnel screen at the back of the screen unit. Verify how the screen is attached to the TV, and carefully remove any mounting tape or other means of holding the screen in place, taking care not to mar the other parts. Put the new screen in place using the reverse process, then close the TV and test to make sure the new screen works. While the TV is open, consider carefully cleaning dust from internal parts to improve overall picture quality.