Four wheel drive not working properly

Bought the truck listed above used, super cab.
Replace transmission runs very good.
4 wheel low got stuck on me, I had to work so I shut truck worked for a couple hours, before restarting truck I got under transfer case and gave the solenoid a light couple of taps with a hammer, put in 2 wheel high started truck and it was okay, I don’t know the trucks maintenance history, should I change the transfer case oil? And do you think that was the problem? Also lots of snow that day. Under truck was very snowy. Thanks so much, Gerard