Step 1: Why Would I Do Such a Thing?
Luckily the boards were fine, so rather than replace the corroded components I opted to use a 9v instead.
The specs are the same (when you open a 9v up there are usually 6 x 1.5 batteries stacked inside) and I keep a ton of 9v spare around for all sorts of things anyway.
Step 2: You Will Need
A nice full 9v
A drained (or sacrificial) 9v
Dremel, or something to cut plastic
Step 3: Scrapping the Drained Battery
If you dont (like me) then you can easily make one from a dead 9v.
Just carefully cut the casing away, starting from the seam at the top and peel it away in small pieces being careful not to damage the plastic surrounding of the terminals.
When you're about halfway through everything should just slide out.
The top should just lift up easily and be connected to a piece of flat wire on one side, just cut that off & keep the top.
That's the only part you need.
Step 4: Connecting It Up
I added some heatshrink and a covering of hot glue to the connector and hot glued the wires down in a few places along the way make it a bit stronger, seeing as they were not intended to be moveable.
Nice and easy, all up took about 5 minutes.
Time to make it fit.
Step 5: Clean It Up and Make It Fit
Luckily for me there was no hardware under the battery casing, so I simply grabbed the trusty ol dremel and cut a hole through the bottom.
It ended up being a bit close to the edge of a board, so I put a couple of pieces of electrical tape on, just in case.
Fits perfectly, lid closes and doesnt rattle, lovely.
Step 6: Done!
After a few hours "testing" its working perfectly.
From the scrapheap to the music room in under 15 minutes for the cost of a flat battery.
Hope this helps.