I''m not familiar with E25 boats, but I do have a centerboarder and think you have a problem, from what you described. You should probably be looking at least a couple of feet of line running out when you lower the centerboard.
What may have happpened is that marine growth has attached itself to the centerboard, making it stick in the case. This is why you want to raise the centerboard fully each time you come back to harbor--to prevent barnacles and other stuff from growing on it.
Another possibility is that you are trying to raise and lower the board when you are under sail, and the pressure of the water pushes the board against the side of the case, making it difficult to drop it or raise it.
There could also be a problem with the winch. I don''t use a winch, but just have a few feet of line that I pull or let go, so its pretty clear to me when the board is up or down. If there is slack in the line, then the board is probably pressed against the case by the water. Pointing into the wind usually relieves the pressure and allows the board to drop fully. I then adjust the board to balance with the sail, providing weather helm or lee helm or a balanced helm, depending upon what I want. (This is a catboat--just one sail.)
If you haven''t hauled the boat since you bought it, I would suggest a short haul to see if the centerboard is dirty, what the draft is when it is down, if gravel is stuck between the board and the case, and play with the winch to see what happens.