Alex got there before me, but heres a link to a site, has a few photos on it too.

http://www.wa4dsy.net/robot/drillmaster/index.html

To add to Alex's description there are also two small clips in the bit where the battery clips in to that you need to take out.

I actually just bought some of the grub screws you need to get hold of today. They are M5 5mm grub screws.

I got them from here :

http://cgi.ebay.co.uk/m5-x-5mm-stainles ... _837wt_907

but I haven't done the mod yet, so cant recommend them or otherwise though i'm hoping they'll be fine. Though if you want to wait I'll get them within the next few days and let you know if they suit. Jamie recommended that size to me and he has done it before so i'm sure they will be fine.