I am i the process of replacing my cam shaft cover gaskets on my XJR 2002.
I have a couple of questions (probably related to all models) and a couple of comments specifically on supercharged models.

Questions:
1. I am changing the gaskets because I noticed some oil in the spark plug holes. I inspected the current gaskets but I could not find any cracks in the spark plug rings. Anything else I should look at before closing up (with new gaskets of course)?
edit: to be more precise: there is a little oil residu on the bottom of the sparkplug holes. The ignition coils seem dry and clean.
2. I noticed some smudge where the bottom part covering the timing changes is bolted to the cylinder block (not sure if I have names of parts right, see pic). There is no indication of an oil leak engine bay below is completely clean. Something I should pay attention to?
3. Chain tensioners seem to be ok. They are plastic (burgundy red). The engine was built 09/2001 and has done over 160K miles without issues.

Comments:
Thanks to Roberts videos, replacing the cam cover gaskets is a quite easy job.
(left)
(right)
Just a small add on for supercharger models:
1. No, you do not have to remove the supercharger. Some bolts are a little more difficult to reach and the coolant hoses get in the way a bit but it will work.
2. Supercharger models do not have the plastic cover as shown in the video. Instead there is some metal plate bolted to the cam cover (bolt 2 & 4 on RH and 3&5 on LH).
You will need to loosen (not undo) these bolts with a 7mm to be able to push the metal plates back and to proceed with a 10mm to undo the cam cover bolts.

Thanks for any help on my questions!