I would be wary!
Although it is my 'go to' glue for most 'rigid' things, Araldite can struggle to get a grip of some plastics. Even if it does get a good grip on the plastic of the arm I would devise some form of permanent mechanical splint. e,g. to repair a broken fridge shell I used Araldite and a bamboo chopstick, the chopstick being glued and permanently lashed into a groove in the shelf, the groove (existed prior to the repair) runs across the outer end of the break.
The above said, for an arm and especially if you wish to keep the warranty valid ( I presume a DIY glue job on an arm endangers the warranty), I would consider replacing the arm which probably means a 'pro' repair.
If you have care fresh then consider using that but ask that the cost of a "you bear the repair cost " repair be assessed before it is agreed that care refresh be utilised.
I have read that some repairs cost less than the care refresh excess.