Not everyone lives around the corner of a part shop or has the budget to get the, often overpriced, parts. So with a but of patience and proper (YES PROPER) use of liquid gaset, you can come a long way.
First of all, try to make the rubber gasket as clean as possible. Get rid of the dirt and in this case the old liquid sealant. Please be careful with solvants. Try to remove as much as you can with your fingers and warm water. If you need to use a solvant, test it first!
Also make sure you determine what is gasket and what is stuff you need to remove. In this case, it is quite clear, but stay alert.
There, all done. No more loose fragments.
I am using VersaChem's Super Blue Silicon Gasket Maker, because when used right, you can use it for anything. If your gasket shows a tear, clean it out well and fill it up (and glue together) with this stuff. Another reason for using this is because I am a fan of this product since 20 years already. But use it sparingly. Please xD
In this case, I applied the blue stuff to the cover and wiped off the excess. Then I put in the gasket and again wiped off the excess.
Next I cleaned the surface of the head properly with some brake cleaner on a rag and removed any old gasket and dirt there as well. I applied a new THIN layer of blue stuff on the other side of the gasket and carefully put the cover on the head. Check after tightening the four bolts if you have to wipe off some excess blue stuff still. One reason for that is that it does not look pretty. ;)