Should be the same as on other Alfa models - the mirror/glass part pops out.
Best way to do this is to use the window suction mount from a GPS to grip and pull the glass forward - and then use a plastic spatula to kind of help it along as you are pulling it.
Set the glass from the mirror controls to its innermost angle to get in behind it with the spatula. It will sound terrible as you are prying it away, but that's normal.
Be clear that the risk of breaking the mirror glass is about 30% - go slowly - but you can order just the glass if it breaks.
PS. I have read on this forum in the past, that spraying copious amounts of lubricant into the mirror sometimes solves folding issues. When the mirror is in the folded position, I think their are holes/gaps underneath at the base to insert an extended nozzle to get the spray inside (I could be wrong). Then just spray lots in and see it is helps - worth a try before taking the thing apart.
Last edited by VeloceRagno; 19-08-16 at 08:58.