My (old) starbucks barista machine works just fine. I do regular cleaning and descaling so nothing is plugged up. But now when the pump is on it has started making a new noise. This is like a louder version of the normal sound it makes when brewing a shot. I'm thinking it might be a bearing wearing out but not sure if the pump even has bearings. I can replace the pump but would rather not if that isn't the problem. Any troubleshooting suggestions?