RE: Tx Rx crystal/freq mystery
Ok,, different view point. It is possible to swap Tx crystals and have the system function normally. However it sounds like you have a problem and might have confused it by swapping crystals. You can buy extra Futuba crystals and or if you prefer sent the tx in and have someone convert it for you. I have sent in rec.'s for repair and the same rec's came back, "repaired" twice, but was still broken. I don't know what was done to it or perhaps just looked over and returned. But I am not at the point of "not repairing rec's.". When I have a rec. issue I just purchase a new rec. I have at least 5 rec. on the shelf that possibly could be repaired, but their cost is so low compared to crashing a big model.
I would reco you get a KNOWN good rec and TX. Then fly that. Then switch only 1 component,, such as the rec. and use the KNOWN GOOD crystal. This way you are making only 1 change. Prior to flight you should range check with the engine running. Don't discount battery switches and defective batteries can also cause problems. This is why you must start with a known good system and then only change 1 item. I would also reco,, you not repair receivers. I have never (in 37) years had a crystal go bad, but many receivers. Only 1 tx ever went bad and 2 crashes from buss bars in batteries failing.
If you swap rec,, you can reuse your crystal in the test rec. with little probability of the crystal being bad. Hope this helps you sort all the 'stuff' out.. Jim