Homeworks Series 8

I have a client with a HWS8 system that's about 13 years old. Twas working great but recently experienced some hiccups.
The system consists of 6 dimming modules, 2 switch modules for about 30 total loads from the panel. Then there are an additional 20 standalone Maestro style dimmers.
Everything works, but several scene buttons don't seem to be able to communicate with the standalone dimmers. They are still fully functional from the switch, but the keypads are unable to get them to do what they're supposed to. House is still using traditional lamps and everything except 3 switches seems to be in order. Anything I should check out first? Is this signs of problems developing on the system? I'm not sure where/how to start as nothing has changed, aside from a few things being unresponsive.

Thanks!

There is a H48 interface in the system somewhere. It could be stand-alone (in a panel) or internal to the processor. This allows the S8 processor to talk to the Maestro controls. It could be unplugged or have 1 or more outputs damaged. If you run the diagnostic, it will list the devices it can not communicate with. You can then determine if the output is bad or just a couple of devices.