How to silence a noisy solenoid
UNPLUG IT!!!
I think these noisy buggers and their service history is one of the reasons (as is cost) that Sears took softener, bleach, and detergent solenoids out of most all their machines but a but a very select few by 1981.
Actually, it will be interesting to know if anyone has a better solution. My treatment for this in the past has been to replace the solenoid. Fortunately I've only had to face this a couple times.
Gordon