There are seven.
1. Just forward of the mast base is a one-inch hole in the white glass sole. Under it, six inches down, is a keelbolt that's impossible to see. I think access to it is through a side-cutout in the locker beneath the banquette. I have a rather ragged factory square hole there, for which this is the most likely explanation. A flashlight reveals a bolt.
2. One bolt in Bilge aft of the mast.
3. Two bolts in deepest bilge, upon which the bilge pump sits.
4. Two bolts in the next bilge aft, from which the manual (Whale) bilge pump draws.
5 One (smaller) bolt in most-aft bilge, under the companionway ladder. On my boat this is partially covered in tabbing, or other factory sealant, and is hard to identify.
When you haul the boat, keep some water in the bilge. Arrange to leave it in the sling for a while. See it the keel joint weeps.
Any attempt to tighten the keelbolts would have to be in the cradle. I suppose it is possible, but for me that would be a boatyard job.