ouch! they can get overextended and kinda lock up."Because something is wrong" is the answer based on the limited information in your question.
I rebuilt a piston years ago and didn't take into consideration that at full extension, you need a pocket for fluid to get into for it to move the cylinder. It owuld sit, bog down, then pop back. I cut a chamfer around the edge of the piston to allow fluid to get behind the piston and the issue was solved.ouch! they can get overextended and kinda lock up.