I've ordered a #6 screw and will test it when I get it.

I noticed that the 13 mm block has worn down a groove into the hinge plates. I assume this happened slowly but probably accelerated after I lost the shims.

I'm not sure if the groove had worn flat or convex from the rocking. I'll try sanding it down since it may prevent the latch from closing fully. I'll also try to chamfer the edge of the block.

I'll shim the tips of the tabs again but still leave about 0.05-0.1 mm gap since it would be dangerous if the 13mm block wasn't touching the hinge plates and the shims fall out again.

Such a bad design. Wish I had replaced the lost shim earlier, then the hinge would have been just like new.