So I notice this year that I need to pump my brake handle a couple times to get the sled to stop. It feels like there might be air in the lines. This didn't happen last year. I putt in a new set of brake pads this weekend and blead the lines. Brake handle was firm but later in the day when I was riding the same thing happen, I had to pump the handle a couple of times to get brake pressure. Any idea on what is causing this?