Is it under warranty? If so, this becomes a no-brainer, definitely send it back. If not, I'd probably try G&G Communications rather than Whistler, and specify a full-circle BNC connector, which is more durable than the cheap spade-type all scanners come from the factory with.
As far as difficulty level...only you know how good your skills are. There was a time when I would have tied into such a repair without a second thought. Nowadays...hands aren't as steady as they once were, eyesight also not what it was even with corrective lenses, and the parts are a lot smaller now. I'd just call G&G, they have a very good reputation on here, for both quality work and reasonable prices.
But you may be capable of doing the work...you'll have to judge for yourself.