On your boat you have in each cabin a line of lockers or cupboards located just below the level of the main deck. Look inside each one and at the part of the locker furthest outboard you will see in the upper corner two strips of plywood, one along the underside of the top of the locker and one along the inner edge of the most outboard part of the locker. Each strip is secured with two small screws which unfortunately were ordinary iron screws (on my B36(2002)), though that might have been something done by the boats original owner. Undo those screws and the two pieces of plywood can be lifted out. Wrap a strip of masking tape around each pair and write on the tape which locker they came from (the lockers are of differing sizes so you will need that information).
The stanchion bases are usually secured with long thin bolts of such length that some extra long socket spanner’s will be handy. You will need, someone to help you with this job, and some string to attach to any tools you use in order to recover the tools that get dropped down behind the backs of the cupboards. Remember to tie the string to each tool before you use it. Once the stanchion base has been removed, thoroughly clean the deck area that was below the base, and use a butyl self adhesive tape to bed the base on when it is renewed or returned. This is a time consuming and very awkward job to do, but once done it will cure any leaks from those bases.
IN PARTICULAR, ONCE THE BASES HAVE BEEN REBEDDED, ENSURE THAT NOBODY USES THE STANCHIONS AS A LEVER TO PULL THEMSELVES ONBOARD.
Tell them to hang onto the mast shrouds not the stanchions - on threat of hand amputation to everyone that ignores you !!!