We've recently found two P210's where the shims between the main gear downlock support assy's and the airframe structure have started to "slip out".  To get to the outer attachment bolts (should be secured with Loctite) you need to remove two small, oval panels from the cabin floor, just behind the door frame.  These panels have a gasket (for cabin pressure, of course) but are also very heavily sealed-in with pressure sealant, which is very difficult to remove due to the small working area available.  Why are they so heavily sealed-in?