The fact that they are all in a row is pretty indicative of a ribbon chord problem. Keybeds have small ribbon connectors that are split into regions of 5-10 keys. If anything happens to a range of keys like this, you can be pretty sure a ribbon is at fault. Thankfully, the most common cause is that it's just become slightly unseated. One wire at the end of the ribbon that reports the velocity of each key isn't making contact, so the controller thinks it's getting full velocity every time. I'd put money on that being the cause, it's a pretty classic problem, and easy to fix:
Open up the board, and locate a ribbon that comes closest to that group of keys. Try removing it, and putting it back in. Be careful, they usually don't have an actual plug and can get damaged if you're hard on it. Wiggle it back and forth until it's all the way in and looks tightly seated.
I've never had this happen to one of my boards, but I've fixed other people's boards that exhibited the same problems you're describing. It's a common problem you'll read about across all models, though mostly unweighted boards (88key boards often use a different system).
