I feel your pain... Unfortunately, I can not see the pictures you posted, but I have some information to transmit that you might find useful.
As Alexandre said, there is no need to remove the motors to get the winch apart for service. You just need to remove the "frame" from the base.
In the attached photo, I have highlighted the bolts that secure the frame. The do NOT go through the deck! They are threaded into the base. They are NOT the bolts that held the nuts you removed from below. Those bolts are the ones that secure the base to the deck, and can not be removed until you get the frame off.
When the proper bolts are removed the frame will lift right off. If the bolts are stuck are stuck, and a few of mine were, heat them gently with a small torch flame. They will back right out. When you reassemble them, be sure to put on some Tef-gel so they don't get stuck next time.
Great Harbor Cay, Bahamas