Mine mounts near the top where the connections come out at :shock:
If yours mounts near the ground I would guess someone modified you wiring harness because the wiring harness runs from the release mechanism up through the inside of the GU and out near the top. If you bought these used and the mount is near the bottom you might want to check the wiring harness.
The only time I have had an issue with TT receivers is when I train in a pasture that has 9 cell/tv/radio towers surrounding it. Sometimes they are interfered with there, but always work anywhere else.
I talked to TT about this and they said that because of the huge increase in cell towers (sometimes you don't even know they are there because they don't look like towers) that a lot of the "hobby" frequencies are suffering interference. I also asked a friend that is an RC airplane guy and he said he has seen similar issues with RC transmitters.