Hello Sailnet, can anyone help w/ DS 20?

[Jesusphil]

This week I purchased a one-owner DS 20 built in Ontario, Canada in 1990. It might have been the last one of these hulls built. The centre board has been 'stuck' in the up position for about 12 years. The owner had the suspension cable replaced at that time, but it was replaced with one of a larger diameter than the original and consequently does not rewind on its spool correctly and looks more like a tangled birdsnest. The cable is slack but the board refuses to come down. I went underneath in 5' of water and clamped a vice-grip on the 1 1/2" of exposed board but could not even wiggle it. The pivot point (or pin?) is completely hidden from view, inside or out so I really don't know what more I can do short of excavating.
If anyone has any first hand knowledge of this model or this problem I would sure welcome some input.
Thank you.