Usually it's the thread in the aluminum head that gives way. Pull the cam off - if you remove the chain and the other caps, then rotate the cam so that the nearby lobe is pushing down a valve, you get enough "up" force to remove the stud.
Then helicoil to repair. Can be done in the car, but the risk of stray metal in the oil is high - it's aluminum so a magnet won't catch it. Use Locktite red to install the helicoil and stud.
I've also pulled the cam cover studs out of the top of the caps. At least you get to work on the bench for these. Check for roundness of the cam journal hole when you do this.
The same thing happened on my engine! Does anyone know the thread pitch on the cam cap studs where the stud screws into the head? They look like 8mm diameter. I need to buy a helicoil kit to repair the stripped hole, is it 8x1.25?
I've fixed these a number of times in my garage for the price of the drillbit and helicoil kit. Remove the cam, pack rags around to keep any stray chips out of the oil, etc., put some grease on the drill bit to capture chips, and clean it up real well before you reassemble. It's nervewracking to think about, but not that big a deal to actually do if you have a good drill, steady hand, ability to drill and tap straight, etc.