[quote=Enso]
Manchester's telekinesis should be powerful, but can't reach its full power unless a certain condition is met, maybe extreme emotional trauma is its trigger.
[/quote]

Or have a mental inhibition. (Think like what happens if Jean tries too much, she passes out or injures herself. So, brain hemorrhaging or total failure for overstepping too much may work. Telekinesis in Marvel is heavily limited since it is not conditional on object affected.)