It depends on WHY the ratings are low. There are two ways to look at it. Are the ratings low because they are stubborn and don't do anything? Or are they low because they are tough, principled, and stand up for the right thing even when it isn't popular? They know that much of the nation is whipped up into an anti-gun frenzy right now, but they know their job is to be the influence that remembers how important the principles of freedom are, even when much of the rest of the country isn't thinking about it.
In my case, I will continue to reward and support my representatives for opposing more spending and standing up for gun rights. Even Utah's lone Democrat, Matheson, is doing the right thing. (The NRA spent more money on him than any other Democrat.) So yes, even if what they are doing is wrong on a national level, it keeps them popular within their constituencies.
The gridlock occurs when people vote for someone because they are a really swell guy, having no idea what they actually represent, and then don't understand why they continue to do things they don't like.