Our church has a Sanyo PLC-XP55 projector. A few weeks ago, it started having vertical rows of horizontal line flashing on the screen. The lines would disappear the longer the projector was on. As time has gone on, there are more lines on the screen, and they take longer to disappear. The lamp has been changed and the filters cleaned. This has not helped. Does anyone have any suggestions as to what the problem could be?