Very smart idea without voiding the warranty on the Pro Pointer. If people are having trouble finding mercury switches (they are hard to find with EPA regulations these days), visit your local junk yard and look under the open hood of some older cars. Like 1980's or older probably. They often used mercury switches to turn on and off the hood light when you opened it. More modern cars use(d) ball bearing tilt switches which don't work nearly as well.
I've used the Vibraprobe and found it's automatic on/off function by tipping upside down or such to be a real pain, so I won't be doing the mod, but I can see how it would save on wear and tear on the Pro Pointer's on/off switch, as that's the most common problem that goes bad on them.
Sidenote: I am a big fan of night fishing for catfish, so I made a bite alarm to hang on the tip of my fishing pole using a mercury switch. It's housed in a little black radio shack project box that I just hook onto the tip of the rod, and can remove before setting the hook. I have a two position switch on the box. Off, and then flipped the other way the mercury switch can energize both a piezo buzzer and a large LED bulb at the same time. Works like a charm. The trick is getting the mercury switch at the right angle so it will energize at the slightest bump. I just wrapped the mercury bulb in a bread loaf twisty tie and then bent the tie until I had the mercury bulb almost to the point where the mercury would make contact with the internal leads. I run it off a car remote door/alarm battery found in key fobs. Can't remember off hand but that little short battery is I think 6V, so it provided the higher power I wanted for the buzzer and bulb, although there are ones that will work fine off one AAA battery at 1.5V. I just wanted the shorted battery for a more compact job.
