hi. I own 86 burbon with hydro bost. My breaks don't operate well after they going hot. It looks like breake pedal don't return to his off position. It returns slowly and the brakes operates when i start to drive. If i push the pedal up with my foot the brakes stop braking immediately. I suspect hydroboost unit or maybe brake master cylinder. What do you think?? If hydro boost became to have malfunctions, i considering switch to normal vacum operating brakes. (i drive on gas now) But i discover that two different power brake unit are: w/JB7 and w/JB5. What is the difference? With one is for me? I suspect that if my car is equipt with hydrobost jd5 - jb5 should work fine, if jd7 - jb7 woul be ok. But how to recognize what hydroboost system is instaled in my car??