Uher 4000 L
 

New message, different machine(s). I have two questions, so I'll post them separately.

Number 1 is for a Uher 4000 L recorder belonging to a friend. It worked fine until he left if plugged in and powered on for several days. During that time it developed a loud buzz from the speaker. The only way to turn off the buzz is turn off the machine.

Any tips on what components might have failed?