When tilting up, does tilt motor stop running or keep running when the up motion stops? If it stops running, 99% chance it is the tilt limit switch on the left side of drive shutting it off (like it should). The trailer switch bypasses that switch so it can continue rising to the upper limit of the pistons (when engine is not running).
If it keeps running, without hitting the trailer switch, there is a mechanical problem stopping it from rising any further.
