I am trying to attach a little drawing of what I did to mount the reed sensor. I hope it takes.
First of all, I got the reed sensor from Radio Shack. It had four wires from it, the two on each end were the ones. I cut off the other two short.
Basically I got a one inch by one inch by about a foot of aluminum angle "iron" from local hardware. I mounted it across two of the bolt holes on the heavy brackets that hold in the worm gear. I bent over a one inch flap and drilled a hole through it the size of the bolt going through it.
Going through the "flap" was a 1 and 1/2 inch nylon countersink screw with two nylon nuts, kind of inexpertly depicted in black. the thing holding the reed sensor is a nylon "spacer" that I drilled out so the reed sensor would snap in there snug. I also cut it off lengthwise, leaving a little more than half of the spacer, so the reed sensor would kind of snap in there and hold as I experimented.
I drilled through the center of the spacer as depicted and also usedd a little bit bigger bit to give it a countersink . It wasn't enough and the head stuck into the space where the reed sensor would sit, so I had to grind off the head some, but not so much as to make it not hold. Something I for got to depict is a nylon nut up against the spacer.
With this mount, I could move the reed sensor further away and closer to the magnet wheel. I could twist the spacer to find the best angle. I could twirl the reed sensor in the spacer until I put its best face forward. When I got that done, I tightened up all nylon screws and I crazy glued the reed sensor in place.
It's worked flawlessly for months.
Hope it helps.
Sorry the image is so small. Maybe you can save it and zoom in. I just tried it. I think it might work