Power trim on a Yammie 2-stroke 30D... now that's pretty rare.
Raise the engine on the level (support it as a precaution), then undo the filler plug on the power trim. You can top up with Yamaha Power Trim Fluid or Dextron II ATF. Use a little marine grease on the ram seals. If the screeching persists it may need new seal kit.