Sorry, I should have included that. It's a 1994 850T. I worked on it yesterday and found that I could remove the sensor without removing the plate. While it would have been MUCH easier without the plate on, it is possible to use a crow foot O2 sensor socket to get the sensor loose. It then took a combination of the socket and a crow foot wrench head to get it tighened back in. Not taking the plate off also requires running the sensor wire around the plate which I did not want to do but felt it was the lesser or two evils. The other route required me to grind off the bolts for the plate and then decide if I was going to just leave it off or find some way to get it bolted back on. As I said in my earlier post, the bolts just spun in place so the nuts had apparently broken loose from their welds. I'm guessing at this since it is to confined to see what the bolts thread to. Anyway, its done for now. Thanks for taking the time to look at the post.