Futaba has isued a service alert on some models of their 2.4gig Spectrum radios.
Here is the link
http://2.4gigahertz.com/techsupport/service-advisory-tm7-7c-6ex.html#list
The gist of the advisory is that a number of 2.4gig Tx were issued with the same 8 digit code. The code should be unique to each Tx. The problem is that 2 Tx with the duplicate code would affect each other. This is exactly the problem that the 2.4 gig Tx are supposed to avoid.
The link also lists a number of hobby shops that have been set up to diagnose a Tx. It sounds like the set must be returned to Futaba for the fix.