Hello, my name is***** have a couple of suggestions for you to try.
- If it hasn't been used in over 20 years, make sure you get a couple of Air Cans and try to vent every opening this projector might have....It's not about just the dust the internal components might have accumulated, but it will help get the moving parts moving again.
- Before you do so, make sure you take apart any Removable pieces to make the job more efficient.
- If you want to get into it even further, here is the link of the Service Manual that you tell you Everything about this unit and how to Service it....Just take the proper precautions as this unit could be internally faulty.
Hope that helps.