clean it and put it back together?
Don't have the manual stop lever?
You could also put a ball valve in the frame to filter line pretty easy.
My friend had a Cummins you had to choke to death by squeezing the supply hose, it was pretty visceral.
VE Cummins supposedly works, but Summit has Bosch...
http://www.summitracing.com/parts/bch-0330001040
Are you sure it's not the wiring? that has a lot more problems than the actual solenoid.