[Destroyer]

Sometimes I just cannot figure out this website. I swear to God, I made a long, detailed post right after Scooks first post, explaining what to look for and how to fix it. Yet when I look for that post it's not here. This is not the first time this has happened either... there are at least 4 other posts that have disappeared the same way.... <sigh>

Ok, end of rant.

Most of what I said has since been said by other people, so I'll just skim over it. First, check that the trim motor runs when you turn the switch or push the button to make it work. If it doesn't run, check for corroded connections, or a blown fuse. Make sure you have electricity to the unit. Next, if you have power but it still doesn't work check the motor itself. Like Cfelton said, it might be the brushes or the motor might be bound up from just sitting. Make sure it turns freely.
If the motor runs, make sure you have enough fluid in the reservoir. Lack of fluid will cause air to enter the lines and stop the rams from working. Add fluid as necessary.
If you have fluid, check for leaks in your hoses.
If there are no leaks check the rams themselves to make sure nothing is binding them. When they are unbolted, you should be able to pull each piston rod out and push it back in manually. If they move freely then check that your outdrive is not stuck. You should be able to lift it manually when the rams are unbolted from it.

Good luck with your project. As has been echoed by others, pay attention to anything that Spareparts or Thefermanator might tell you. They do this stuff for a living and have a wealth of knowledge that they share freely.