99 Taurus shift solenoid replacement question

Haven't posted in a while but have a (maybe dumb) question. Working on a 99 Taurus for a friend and replacing the shift solenoids. We got some used ones as it was a deal on all 3 plus the EPC and Tcc solenoid as well. My question is that the replacement shift solenoid a are a little loose in the sockets, how snug should they be? And would it be wise to find new o-rings? This is new territory for me, so any help is welcome!!