Dale,
I guess I missed a couple of things reading your post. Did you replace the seal in the trans? Also your pictures only show the cover being removed. In order to properly clean up the solenoid the internal components need to be dissassembled and cleaned up.
You can use some light grease when you reassemble the plunger. It is indexed so you can't put it together wrong.
It appears to me that seal in the solenoid is held in by the
surrounding boss being peened over. As I mentioned I have never found it necessary to replace this seal as the seal in the transmission solves the problem. I have never found any other gaskets between the solenoid and the trans in all the ones I have rebuilt. Of course someone may have tried to stop a leak using one but I doubt it worked.
Fred