Tested my TRS drive and moved it out but it wouldn't move back in. When I hit the IN switch the pump would make noise like the drive should move but the drive wouldn't move. It would move out but not in. What do you guys think could be broken?

My Formula had the same problem and I found it to be the pins in the bell housing. I put some lube like PB Blaster on them and the problem went away. As you hit the switch try having someone push down on the drive to see if it will move.

Could it be anything else. I did check the hydrolic fluid and that was fine. Also why would the pins cause this problem?

No no, have the transporter from Hyperfishing's bad experience move it and he will bend the drives into proper place

Come on, Seriously.

I had a little water and air once in my line and had the same problem... changed the oil and worked fine after.

Low fluid level in your trim pump tank would be the first place
to start.When you trim out all the oil leaves the tank and pump
gets air bound.If not sounds like a check valve problem in the pump.

I checked the fluid level when the drive was stuck in the out position and it said it was full. So how should I trouble shoot this. How do I determine if it is a check valve problem?

The level should be at the full mark when all the way in.
Try reversing the lines on the pump to see if the opposite happens.

The pins start to rust a little or get tight and there is no grease fitting to keep them lubed up. When you hit the up button it forces them up but when you hit the down button there is no real force. Hope this helps.