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. I eased off the top and bottom, bending slightly, so that I was able to remove it.
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.
2bits: the RC relies upon a clock mechanism for the shutter and is, in my old-fashioned opinion, MUCH more reliable. This is the reason that the Nikon FE is priced drastically lower than the FM. And the reason that the Pentax ME is priced drastically lower than the MX. Sometimes old-fashioned springs are just more reliable. (Check the prices on MINT Nikon F2 bodies. This was the LAST Nikon body to use springs to time the shutter.) - David Lyga