[Collins] KWM-380 synthesizer failure

[Graf Ulrich Com MD PD ST 2 ULM 1]

Good morning,

I've got a sick KWM-380 of a friend on my table. When I switch it on it beeps three times as normal to signalize a locked pll. But then it starts beeping continuously with a kind of distorted, non sinusoidal tone. Frequency display shows zeros with an open 0 at the first place. Frequency tuning is not possible. Starting trouble shooting according to the manual allows first steps only which all seem to be ok. Then manual asks for frequency tuning to specific settings which is not passible. Any ideas where and how to go on from that point?

73 Uli, DK4SX