LG LDK-300 -some analog lines not ringing

[Pedala]

Hello,

We have a LDK 300 system with two cabinets running 3.6 firmware with both analogue and digital extensions.
Cards in cabinet 1:
-DTIB12
-PRIB
-LCOB8 (not used anymore)
- 6 x SLIB12
Cards in cabinet 2:
- 7 x SLIB12

Starting yesterday some of the analogue extensions don't ring anymore. If you pickup the headset you can answer the call.
Can you help me with were to start diagnosing this problem?

 

[Pedala]

I solved it by replacing the caps on the RGU unit