Loose lense mount?
 

My XL2 shuts down (with check lense message) if I put even moderate pressure upwards on the lense. The electrical contacts are on the bottom half of the lense mount and a little bit of upward pressure on the lense seems to break a contact ( I use the 3X wide as well as the standard 20X) and give this problem. The lenses do not seem to be unduly wobbly and the rest of the time and the picture is unaffected but if this happens at a critical time can be very annoying with lost footage. Does anyone else have this problem?

You're not saying where you are, but I'd advise sending your XL2 to the nearest Canon factory service center. If you have another camcorder -- any kind will do -- shoot a short video showing your XL2 which demonstrates the problem. Send that tape along with your camera when you send it to service. That'll give those techs a better idea of the issue you're facing.