OH No, another "Monday, Friday, or day before/after a holiday" boat! Did your mast step suddenly crack through the cuddy "floor" causing the mast to drop down a few inches?? Happened to me (and a few other DS II owners!) and let me tell you, the BANG when the previous owner's inadequate repair let go was a bit frightening, even to a seasoned sailor!! Apparently, on some boats, the plastic pipe that is placed under the maststep to carry the load of the mast down pressure to the inside of the hull was misplaced, mine was about 3" or so forward of the mast step! I fixed it initially by adding an aluminum plate (about 12" square) between the mast step and the cuddy floor (had to remount the CB lifting control line as well, I tapped the plate and used short machine screws in place of the original sheet-metal screws to secure the eye-strap and block). The 3/4" plywood under the cuddy floor (about 8" to 9" square, maybe a little bigger?) had also rotted out over the years prior to my purchasing the boat and I ended up cutting an access panel to one side and aft of the mast step to allow me to replace that. About 8-9 years later I discovered the plywood that I put in had also rotted out (I guess I had not saturated it enough with Epoxy), this time I rebuilt the area correctly with a larger plywood panel and I move the pipe so that it is now directly under the mast step, coincidentily also raising that area of the cuddy floor and thus the mast step a couple of inches (area had sagged down sue to pipe not really being tall enough once the plywood between it and the underside of the cuddy floor had disintergrated.)
I hope I'm not scaring you, this is not a catastrophic failure, but will require some possible rebuilding under the cuddy floor. For now, adding a metal plate under the mast step may keep you going until more permanent repairs can be decided on. However, if you actually have any cracks in the hull due to this failure......... repairs are more pressing! Here are a few pics of my boat to show (sort-of) my repairs. If I can offer any advice, guidance, let me know! I could take some more pictures of my boat, but right now I am 40 miles from her and may not get aboard until Sunday. I have added another drawing, showing the approximate location of the support structure under the cuddy floor (foam-filled fiberglass "beams").