It was the two shims on the right bank front intake for which to unscrew the camshaft.
But for some others you need to remove the bolts of the upper camshaft housing.
I don't believe its necessary to unscrew all at once and tighten them in this special order, but that you can safely remove one at a time. Tighten them with 2,5kgm.
And check the valve pair text to that screw so you don't have to do that twice.
In general it makes a big difference how thick the shims are. With shims above 3mm, they will more likely make troubles getting them out. With shims under 3mm, they go out more easy.
Btw: How does the cam shaft head looks at this worn out shim?