To answer your question about the possibility of a bad Rx or a bad crystal, yes to both. I’m not familiar with that Rx to know if your plugging in the servos right.

Your problem may not be on the receiving end, lets check the Tx side of the equation.

First pull the crystal (right on the front, lower left) to make sure it also says. 72.050. Can’t always believe external stickers on the Tx. I know that first hand. Double check to make sure the antenna is screwed in tight. One last thing I can think of is make sure both batteries have a good charge.