2 of my dash vents don't work right. The horizontal plastic pieces don't close correctly when I use the roller knob to close or open them. From this forum, I've noticed that it is possible to pry them out to replace lights behind them. I'm just wondering if anyone has pulled them out to fix the problem I'm describing? If so, how difficult was it? Also, I've checked for replacement vents, but didn't come across any. Anyone replaced theirs?