Merucry Trim Motor

[cape2fish]

I am planning to replace the trim motor on my Mercury 200HP EFI outboard. I tested the leads from the motor direct to a battery and nothing happens. Plus there is corrosion around the base of the cap.

Two questions but any other information welcome.
Motors seem to be around $100 for aftermarket brands or $500 for Mercury brand, which would you recommend?

I need to remove the motor from the outboard, do I really need to remove the outboard from the boat?

Thanks