You can heat a contaminated sensor with a common propane torch to try and give it some extra life. Don't expect to get it right the first time, you might loose one. I think Bosch specs the max body temp to not exceeded 950F max. Yeah, I know a bad turbo installation will far exceed that, I'm just indicating that there is an actual "never exceed" spec for body temp. Under excess heat conditions there are a few tricks like a tube extender or a copper heat sink that can be used. But I digress . . . Using a propane torch you don't want the nertz cell to glow dull red. It has to get hot enough to burn off the lead but no so hot to fry the internals. I have saved (and lost) a few that way. As already indicated, lead contamination slows down response time. On a close-loop street motor, response time is important. But running a slow sensor on an open-loop, WOT, 2 minute, full pull, is not such a big deal for Bonneville. You will be running data acquisition and even a slow sensor will give you a reading. Just calibrate for reassurance.