So I thought I'd hook up all my scanners (MX4s) to make sure they were all working fine and I noticed a few of them that were a bit more dim than the others. For one of them, the gobo and beam is barely visible. I cleaned the glass and the mirror but the problem still persisted. I've never changed a bulb before (they are supposed to last 9000 hours but I bought them all used) so just want to confirm that this is what is the likely problem. The bulbs run just over $50 so want to make sure that this is the most likely issue.