After you are happy with the parts reassemble them in the reverse order. After the assembly is back together you can use a punch or chisel to crimp the housing back over the washer, this must be done carefully, again, have to protect that soldered wire. You can also use a heat resistant 2 part epoxy to glue it into place, a dime sized blob worked into the edges usually does a good job. After it sits overnight to dry you just add on the rubber boot and test the solenoid function with a 12v source.