Having trouble to figure out any replacement for shut off valve. It started as doesnt stay on until i have to remove te vacuum from valve. Happens when cold temp. Once i removed the vacuum will start and once warms up i can put the vacuum back goes back to normal. Then last 2 mos, even i removed the vacuum clutch is hard. i need to shift to 5th gear and brakes together to shut off the engine. Any possible options or solutions. Thanks in advance