RE: JR 921 2.4 Receiver Mounting
Yeah, a new thread might be best....
But I'll offer a thought; there are/were three different firmware versions for the rx's. The initial release, the first Quick Connect which all the R921's had, and the latest version of Quick Connect where the rx lights flash after a power brownout.
All of the rx's need to have the same firmware. It is quite possible that your Spektrum remote is not the same firmware version as the R921 and it's original satellite rx.
I run an R921 with a JR and a Spektrum satellite on two different models and it works fine.