Power trim malfunction

I have a 1989 200 EXTF.

When I raise the engine up everything seems to work fine. On the way back down it seems as if the trim motor is out running the cylinder's return into the ram. To clarify, what I mean is that I can push the engine down by hand until it reaches however far the ram has (wanted) to receed.

I checked the fluid in the resevoir and it is full.

What do you guys think is causing this? Air?

Question, the tube that runs from the top of the ram to the base of the resevoir, is that a self bleeding device?

[boats.net]

Be sure to check fluid level only when motor is at full tilt up. To bleed air out loosen manual release screw and lift motor up and down manually by hand and recheck fluid.