Ongoing CM intermittent offline issue

[mr-b]

I'd appreciate any views on my ongoing connection problem.
My ntl CM keeps going offline intermittently i.e. on my previous Motorola SB3100 all the lights go off and on the replacement silver one the RDY light flashes (Sync steady).
The CM is offline for anything up to 6 hours and it usually happens every day. I run pingplotter to check connectivity 24hrs.
When the engineer comes round the connection is working, natch, and so they replaced the CM and attentuator to be sure. A network engineer has also called and apparently found an upstream issue and so replaced some modules (I think they were amplifier-related) in the street box and further upstream - but of course after a few hours it went offline again.

Whilst I appreciate that intermittent problems are hard to diagnose, is there anything else that can be done or do I just have to wait for the coincidence of an engineer coming out when the connection is offline?

[mr-b]

As pure luck would have it, another Eng came while it was offline. It turned out to be a faulty splitter in the street box.

Good news then