Since this is an older installation.
Are the wall switches old enough to be before Soft Start?
Where they ramp on and off. Also have a preset dim.
Reason I asked is the soft start have to be handled differently in AHP then the older type.
It is possible you have a power line signal problem. The CM17A sent an RF command to the TM751 and it passed the signal on to the E2 switches. Now the CM15As position in the system maybe on a different branch circuit or the other phase of the homes wiring.
Here is a good set of troubleshooting tutorials.
http://jvde.us/x10_troubleshooting.htmhttp://www.act-solutions.com/PCC/uncle.htmFor #2 We have seen reports of timer problems with 3.271 and 3.236. Many have back tracked to 3.228 and had better results.
There are threads here on how to do it.
Basically from here:
ftp://ftp.x10.com/pub/applications/activehome/Download ahp_updt_204.exe and run it.
Then run the check updates from the AHP that was installed and it will find 3.228.