Being Dettweiller is no longer in business it is really hard to find any info.  Stupidly I had my motor off 2 weeks ago and didn't think about the jack plate at that time.  The jack plate works, but you can hear it cavitate if you try to go to the top.  I assume that the yellow "nut" is the fill port and understand I add some, raise it, add some, raise it until it gets to the top and then cap it and go about my day.  I just don't want to take off the yellow cap if that is the drain in the case that the fill port is hidden somewhere else and out of reach at the current setting.  Anyone have any insight on that?

 

It's basically just a Mercury Tilt/Trim pump.  

https://www.bing.com/videos/search?q=how+to+add+fluid+to+mercury+trim+pump&&view=detail&mid=D06C876CE0B5A1278F71D06C876CE0B5A1278F71&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dhow%20to%20add%20fluid%20to%20mercury%20trim%20pump%26%26FORM%3DVDVVXX

Thanks Keith!  Out of all the boats I've owned I've never had to do work on a trim pump.  That looks simple enough