The solenoid is not difficult to service at all. There are just a couple of things you need to know in order to make it easier and less damaging. Be sure to read about servicing the solenoid in the solenoid section of this sticky: http://www.pbnation.com/showthread.php?t=3457681
However, let's figure out the issue before diving in to the noid head first.......
Did you have any other issues?
Any shoot down? Loss of velocity?
Did it not shoot work in any firing mode?
Did you still have air in the tank?
Was the tank outputting pressure correctly?
Did you try adjusting the velocity screw at all?
I know some of these are real basic stuff but I just have to ask....ya never know
To answer another question I read.......just some Dow 33 or equivalent is dine to use in the solenoid.