I think Vince is probably right about the wire gauge.
The few times I've had to replace one, I just bought some antenna wire from a Hobby Shop, cut it to the same length as the original antenna and soldered it to the RX circuit board.

I've crashed plenty of r/c vehicles and aircraft in my lifetime. Most of the time the RX or crystal will be fine, but sometimes even what seems like a minor incident can damage one of them. Either will cause loss of control at anything more than very close range.
I actually had a receiver go bad in an airplane that I had hanging from the rafters in my garage for a few months.

Really the only way to be sure is to have it checked out by an expert. That or compare your equipment with known to be working units. Can get expensive fast if you just randomly start replacing parts to find the problem.