Start with the saddle. Out it comes. Good riddance.

Next, you take a little socket like this and remove the four screws that hold down the bridge itself.

Now you have this. See, it's hollow inside. What a plus for tone!

Next you take a little adjustable wrench like this and quickly loosen the nuts on 
the inside that hold the studs in place. They'll spin off with your fingertips.

Then you put the adjusting bolt back in for a moment and use a pair of 
end nippers and a block of soft wood to lever the studs carefully out of the face.

Easy does it...out they come. 

Now you have this little mess:

A lot of weight. And a lot of holes that need to be filled before you can go much further. 

It still has lacquer on it - the difference in color is a suntan line. 

Step One is to cover all the holes on the inside.

Sorry for the shadow here, but what I have is a thin maple patch big enough 
to cover all the holes. The guitar had a very adequate bridgeplate already. 

Since the new bridgepin holes will precisely line up with the old ones, 
they needn't be filled, but they do need to be covered.

To glue this patch in properly, you need to make precise marks you can see from outside through the holes. 

Always doing a dry run makes sure you have it right when you actually glue it.

Since the top is old a bit bulged, this patch will go down with a cork-faced caul. They 
sell this stuff at hardware stores for covering bulletin boards.

Here's the bridgeplate patch double-stick taped to the caul which is in turn taped to 
a big C-clamp. It's off-center for a reason. Note that the marks are nice and prominent.

Note: if you were doing a bridgeplate patch on a more normal guitar, 
you'd use one only big enough to cover the bridgepin holes. 

Note also the long line with the two crossmarks for locating it to the outside 
bridgepin holes; the patchwould need to be just big enough to cover 
that area, keeping in mind where the string balls need the real support.

You apply the glue after you do a dry run, right? 

Now put the above rig in through the hole until the marks (see them?) line up with the holes, like this:

You want to make sure it's going in without hitting braces or anything else. 

Use a mirror and a light to check inside. 

Then you clamp it like this:

Now we have this. It still has lacquer on it, and lots of holes. 

At this point, I use the masking tape to define the precise edge of the backside and ends of the bridge, for later reference. 

You have to fill the holes. I use spruce dowel (ex-violin soundpost) for the four smaller ones, and two layers of  spruce - some larger dowel and then a hand-cut disc - to fill each of the stud holes. A bit of spruce gets laid into any chipped-up places too. You want this surface smooth. 

Here's another look at it. 

Now we make the bridge. Click here to continue.