OP, it's not worth the trouble - conversion parts cost more than you can buy new. I retired my very well used Marwi Night Pro 20w+15w dual MR11 bike light 4 years ago, due to obsolescence from maturing LED technology.

You can get an official Magicshine 808 from the largest US seller with latest generation emitter for $85, and a clone for less.

http://www.action-led-lights.com/col...men-bike-light