Intermittent operation of 3 appliance modules AM486

[Rich <rich@xxxxxxxxxx>]

I have a system in my 2600 sq ft home that I use for controlling my
Christmas lights in season and just a couple of other lights during
the rest of the year.

I am having fits with it because of seemingly random control failures.
Although I have read and extensively researched for trouble-shooting
ideas on the web, I cannot seem to locate the source of the problems.
Like many stubborn technical problems, I may have multiple causes.

I hope someone can see my problem and suggest a trouble-shooting
method that will help me.

Specifically here is my system:

(1) Sundowner Controller SD533
(1) CM11 Computer interface, programmed and disconnected from my PC
(1) Wall Dimmer WS467
(1) Wall receptacle SR227
(8) Appliance modules AM486
(1) Phase Coupler/Repeater XPCR

The program in the CM11 turns on all devices at 4:30pm and off at
11:45pm.  This program worked fine last year, but this year I am
having issues with three of the AM486's on one end of my house.

The devices intermittently refuse to turn on and off.  Usually they
will turn on but not off, but sometimes they don't turn on either. One
of the AM486 is more problematic than the others.

Last year I had a simple phase coupler of a 0.1uf cap connected inside
my breaker panel.  In the course of trouble-shooting I discovered that
the cap had failed.  Instead of simply replacing the cap, I decided to
install a Phase coupler/repeater - XPCR.  This device was installed in
a utility box with short connections into my breaker panel.

My trouble-shooting actions:

Swapped the intermittent AM486 modules with others- problem remained
in the original locations.

Changed address of the intermittent AM486 modules- no change

I programmed the CM11 with two fast macros- one to turn everything on
and the other to turn everything off.  Set these to A5 ON and A6 OFF
so I could test from my sundowner controller.  When I issue the A5 ON
and then the A6 OFF , the CM11generates the commands and everything
USUALLY works as it should.  There is a delay of several seconds from
the A5 and A6 button-push and the actual device operations- I presume
this is normal and due to the CM11 interface.

All devices USUALLY turn off with the ALL UNITS OFF from the Sundowner
controller.

Since the CM11 and the Sundowner controller CAN control the devices, I
conclude that the programming is done correctly and that the command
signals are being transmitted properly.  Is that a bad assumption?

The problem is that at the programmed turn off at 11:45, three of the
AM486 don't always shut off.  At that time. the A6 OFF and the ALL
UNITS OFF don't USUALLY work either.

So I have a system that mostly works but intermittently fails.  I have
tested the system using A5 & A6 commands to the CM11 with various
appliances on and off.  I've tried my furness, TV, and all my CF
lights around the house.  I have not found any CF or appliance that is
causing interference.  Every time I trouble-shoot the system
everything works.  Later at the programmed times the devices fail
(remain on).

BTW, my entire house is filled with CF lights.  Last year I did find
one CF that was apparently causing interference but only when it was
turned on.  I replaced it with another CF light and the problem was
gone.  This year I can't find any CF lamps that are causing a problem.

I don't have a signal level meter and really don't want to invest in
one unless there is just no other way.  Really, how much money do I
have to spend just to control Christmas lights?

TIA.  I hope someone can help me.

Rich