Hi crich,
I used a 1.5v SMD LED replacement and very happy with the lumens/brightness and clear white colour. I used a small screwdriver on the side farthest away from the switch and carefully applied leverage pressure until it popped open. A fairly simple procedure. Just use a screwdriver small enough to fit in the gap so any marks or damage aren't visible and a bit of cloth between the bit and the outer housing so no marks are left there.