Certainly BlueTack would not be up to the job – I have tried to use it as a “dam” when employing the heat from an angle lamp to cure some Araldite and even at that temperature it proved less effective than Plasticine.
If you have the time you might care to employ one of the most effective repairs I have managed. It involved an ancient Johnson outboard motor some of the aluminium castings on which were, as a result of too much contact with salt water, moth-eaten to say the least. The castings were first sand blasted and then immediately coated with Araldite. The “immediately” is important as aluminium is an extremely reactive metal, the only reason why it doesn’t burn like magnesium is that it instantly forms an impervious oxide layer. Build a Plasticine dam if need be and certainly use a gentle heat as the Araldite will then go very fluid before it sets and will flow into every crevice.
A quicker, but possibly less durable repair would be to scrape the area clean, (a less effective key than sand blasting), and again apply Araldite and let it set at room temperature.
Lastly there are preparations on the market from the likes of Frost (http://www.frost.co.uk). They do something called “Oyltite Stick” that might do the trick but I have not tried it.