Don't use LocTite - #242 is too strong, and #222 is even a bit much.
What do I use? Fingernail enamel. Works great! It's strong enough to hold, light enough to break easily, and elastic enough to allow for adjustment without reapplication. I use clear for threadlocker on small screws, and white for bringing out witness marks, matchmarks, and timing marks.
(I started out by using fingernail enamel for riflescope screws, and decided it worked really well! Anything under #10 or M5 gets the stuff on the threads, I only use LocTite #222 if it's something I don't plan on needing to adjust from time to time.)
If the screw breaks, I usually just cut the head off with a Dremel and clamp on it with a Vise-grip, once the sensors is off (since I'm probably replacing the sensor anyhow.) If you cut carefully, you won't gouge the housing - and there are usually washers under the screw head anyhow. Using a regular cutoff wheel instead of the reinforced will give you more control over the cut, and the wheel is smaller so you're less likely to hit something important.
"recon" (sic - reckon)(tm) "hihgly"(tm) "seceed"(tm)
"Outback AIDS - Alcohol-Induced Dizzy Spells"