Jim,
This is something that can happen to keel/centerboards sloops. It happened to my friend Wayne's Seaward 22 last year. He brought it to the dock and left some slack in the pendant line. While we were talking, the board dropped down. I had gone under water the previous week and tried unsuccessfully to free his board the previous week.
I have a keel/centerboard O'Day 222 and I haven't had this problem in years but when it did occur it was because I had let her ground out in shallow water. I have an 800 lbs lead keel with the centerboard inside.
What you have is an 1,825 lbs lead keel with a slot in the center for a fiberglass centerboard which pivots on a fiber pin. It's possible that marine growth could have built up around the inside edges of the slot and/or the centerboard, and it's constricting the board from dropping down. A more common occurrence is when the keel grounds out in mud and some small pebbles get in between the centerboard and keel slot.
You could try a couple of things that may free it up. I'm not sure what your board weighs but I think it's in the 60 lbs range. It's about 57.5" long and 18" wide.
If you leave about a foot or two of slack in your centerboard pendant line and cleat it off, just the weight of the board itself may cause it to eventually swing down and free itself if there is adequate boat traffic going by where she is slipped. If not, try taking her into some turbulent water to see if the pendant line tightens up. If it does tighten up, let the line off and let the board drop all the way down. Then raise the board slow until she binds a little and keep working the board until it clears itself to where you car raise it all the way up and lower it all the way down with no binding.
If this doesn't work, you'll have to get a diver to go down with a thin metal type object like a builder's square and stick it into the keel slot on both sides of the centerboard to clear out whatever if binding it up. You could also have the boat raised. If you opt for raising the boat you may as well check the centerboard pendant line and the shackle once you get the board down.
