I have a single axel, 2008 UFP A-60 trailer that apparently the brakes haven't worked on since I brought it earlier this year. I was attempting to change the brake pads when I noticed that they looked brand new. I checked the fluid at the reservoir and noticed it was bone dry. All of my attempts to bleed the system have been unsuccessful. While stroking the pushrod repeatedly I might see a bubble here or there in the reservoir but the fluid level remains the same. Could I have a bad master cylinder?