CMack,
Your problem was incorrectly diagnosed by the tech support person. When one receiver/sensor has reduced range and the others do not, the problem is either a defective sensor or interference at that location only - probably a defective sensor.
The symptom could be alleviated by reducing the emitter level, but as you found out, it created a problem with the two good sensors.
Adjustable emitters are a good idea, since repositioning emitters after they have been stuck down nearly always creates a service call in a few years to replace the stickypad after the emitter falls off.
Best Regards,
-Eric
Eric Johnson
www.hometheaterpro.comPhone 1-800-247-7001