Fluke 87V - no continuity buzzer

[tudorv]

Hello,

i have just bought an Fluke 87V from ebay which works perfectly except the continuity buzzer which works only now and then without having any logic. I opened the case and cleaned the contacts of the buzzer, but still no use. I also used the backpanel from another fluke 87V with a perfectly normal buzzer and it had the same behavior. What could be?
Thank you!