Assuming the crystal in the TX is the original... the Super-7 SHOULD work with the 127DF RX using the 72-10 crystal if the crystals, TX and RX are all good.

Something is broken.

first try the RX crystal in a different RX.

Then try to operate the RX with a different TX.

Then if the problem has not been identified I'd be boxing it up and sending it to Radio South. It'd probably be a $60 repair bill (might be mre... might be less... never much less [&:]) but it would be RIGHT.