That is a young system!! My most used system dates from the 70s!
The system you have has a couple of problems. The record player is fine - do you have the radial Beogram 5000 or the tangential 5005? Getting a new cartidge is very sensible and I would recommend a SMMC4 from Soundsmith. Better sounding than the original and available.
The Beomaster can develop a few foibles - there is a connection cable which runs from the drop down front panel to the main board and this can break. There is also the fact that some components can drift out of spec over the years and need replacing - though this is not that expensive to fix - we have the service manual on site for silver and gold members.
The Beocord is reliable and excellent - you may need new belts but Martin can get those for you if needed.
The CD-50 has a practically bullet proof laser but can need capacitors replacing and the drive belt for the opening door can fail.
The S80 speakers unfortunately tend to suffer from foam rot. This is universal in this era of B&O speakers but may have been fixed already. You can tell by taking the lower grille off and inspecting the surround of the lowest driver. If it has holes in it or is sticky to the touch, it has foam rot. Not too expensive to fix and can be done by yourself if skilled.
Sounds like a disaster area but really is not. The Beomaster 5000 is in someways the best of the 5000/5500/6500/7000 series so you have a good one. Good price too!
Best wishes,