Warranty claims can be handled much more expeditiosly if you take your board back to the Starboard dealer where you purchased it.
Have them take photos of any problems and the dealer can work with the distributor in your country.
The progression is dealer....distributor...Starboard HQ.
As far as freeing up your centerboard, have you tried rubbing the centerboard itself with soap (regular
bath bar soap).
Also rub the soap inside between the lips of the gasket.
Also you may want to remove the pull the entire cassette out and have a look at the side plates.
They need to be snug to hold the correct orientation when the centerboard is deployed.
Give this a try and if it's still too difficult to rotate the centerboard up and down, there may be some
other things that can be suggested.
Hope this helps,