A Warm Welcome to your first posting on Beoworld..
When you say all the other Beocom's are working, are these other beocom's registered to the SAME base which are working ?
If the answer to the above question is "Yes", then the most likely cause of the problem is the RF chip on the PCB of the non working Mark I Beocom 6000.
If that is the problem, then you have two options:-
- Try and get a working second hand Mark I PCB and replace it into the fault Beocom 6000 as the RF chips and therefore the PCB are no longer made.
- Purchase a Beocom 6000 upgrade kit from B&O which allows you to make your Mark I Beocom 6000 into a Mark II which has a totally different PCB and software.