Suburban Water Heater gas will not shut off

One thing you could try for now is fire up the heater and get the little flame happening. Turn off the heater and tap the solenoid a couple times, see if the flame goes out. If it does, do this after each heater usage until you replace the solenoid.
If it doesn't, make a shield out of tinfoil just above the burner tube to deflect the heat. I don't think the heat would bother the wires or solenoid, but a shield would give you piece of mind.