I HAVE removed the top of the XA. There is a plastic part, the sliding door that opens and closes the lens area. This door snaps apart if I remember correctly, but has a ball bearing that you have to watch out for.
But, please note, sometimes the shutter lag is NOT caused by dirt but by a (chip? circuitry?) delay that becomes maddening. Usually when this happens another push on the shutter causes an immediate firing. It is truly maddening sometimes and I have never experienced another camera that acts like this. Of course it does not ALWAYS act this way but certain XAs (and their offspring) do. - David Lyga
Is this post for the other Olympus thread?
I also own an XA, but I haven't noticed this issue.