Bit of an update for those that are interested. I looked into using Devcon which I have used before on engine casings very successfully.
The idea being to fill the hole with putty and once it's set drill a new hole and tap a new thread.
However I couldn't find a product that was food grade. Given that there is a chance the hot water will come into contact with the set putty I didn't want to risk it tainting the flavor or worse.
So given that I have had around 5years faithful service from the 800 I thought it time to retire the old girl. Anyone need some parts?
I am now VERY eagerly awaiting delivery of my new Silvia V3 purchased today from Coffee A Roma, great service called them today and ordered through Julie, and it was dropped off to Aus Post this afternoon.
Can't wait to begin the next stage of my snobbery journey