repairing leaking box of Thorn M open flue boiler?

WE received the following answer to our question: boiler is leaking - corrosion has started?


thus: your boiler has reached the end of its life, needs to be looked at ....water dripping on flame could cause dangerous levels of carbon monoxide... (Many thanks for this, but...)

We were wondering whether it'd be safe if we can waterproof the box, for example using fibreglass or a mix of superglue etc(my partner is a sheet metal engineer)? Are there any precedents for this? One of the (fully registered) local plumbers who looked at it reckoned that his father would simply weld a new external wall to the box... it seems a great shame to get rid of such a simple, superbly reliable boiler just for the sake of one component, its box....
The small leakage is miles away from the flame and we have got a carbon monoxide detector in place - so far everything has been fine.
Thanks.