Yes, so we had this problem with a printer. It did not work very well. Keen on finding the problem ourselves, we disasembled the printer slightly to find the diffusor was physically molten.
Since there is a service agreement on the printer, we decided to call HP Support. The solution we were presented left us speechless.
AA: “Hello, our printer is broken, the diffusor has molten, as in plastic deformed due to high heat”
HP: “Hmm, okay, have you tried a firmware upgrade? This solves alot of common problems”
AA: “uhm, did you hear that the diffusor is molten? nevermind…”
Who is training these monkeys? It seems like the standard behaviour when contacting tech support most places: “Uselessness”