Grab the mainsheet swivel and push and pull to see if the cb trunk moves. Movement here indicates that the bolts holding the trunk cap on are loose. If it moves, watch out for excessive movement where the thwart meets the seat. Any lines that feel rough or are stiff will need to be replaced. It is likely that any boat with original lines needs new ones anyway.
New lines make a boat a lot nicer to use in any case.
The plywood keelson can delaminate where the mast steps if the glass layer is not intact.