DISCLAIMER: The procedure I describe here may devalue your game to some collectors. It could also be described as overkill. If you know how to adjust, file and repair leaf switches, by all means do that instead. I decided that I wanted to bulletproof my Black Knight for league and tournaments, and that's why I've gone down this path.

For each switch, you will need these items:

Microswitch bracket with 3/16" mounting holes (left- or right-handed):
http://www.marcospecialties.com/pinball-parts/01-12356
http://www.marcospecialties.com/pinball-parts/01-12356-1

Williams/Bally Rollover Sub-Microswitch 5647-12693-19:
http://www.pinballlife.com/index.php?p=product&id=829

Williams/Bally #2-56 x 7/16" Microswitch screw:
http://www.pinballlife.com/index.php?p=product&id=230

1N4004 diode:
http://www.pinballlife.com/index.php?p=product&id=173

3/16" clear tubing, or heatshrink tubing

Before and after pics of the switch actuators (as seen from above the playfield):

IMG_6113-453.JPG
IMG_6112.JPG

Before and after pics of the switches (under the playfield):

IMG_6105-129.JPG
IMG_6110.JPG

Mounting the microswitch correctly requires very small movements. The switch-side of the actuator should touch the edge of the slot, while still allowing the full range of motion for the switch. Centering it in the slot is important too, to avoid "sticking".

The PBL actuators are a different shape than the stock actuator for my Black Knight, but I didn't find that it made any difference. The inlane switch still works from both directions. Here they are, old in front, new in back:

IMG_6107.JPG

I like to put the switch diode inline with either the drive ("column") or input ("row") wire, and then cover the splice with clear plastic tubing. The banded side of the diode must face the drive side, but it doesn't matter which wire you put it on. Pick the wire that needs additional length, if you face that situation.

Solder the free end of the diode to the Normal Open (NO) lug, and the other wire to the common ("C) lug. If you get them reversed, it doesn't matter - so again, you use this to your advantage if you come up short on wire length (as I did in the picture below).

IMG_6109.JPG

Is this upgrade worth the hassle? I think so, particularly if you have a bad leaf switch that you're swapping out anyway. A microswitch will never need adjusting or cleaning. Also, I think that the signal to the CPU has a longer duration when the ball flies over the switch. I had a perfectly clean and adjusted leaf switch on my left outlane, and there were several times the ball flew over it and didn't give me credit. Not a huge deal for most games, but if "LAST CHANCE" is lit on Black Knight and that switch doesn't work, it's infuriating.

I welcome criticism of my wiring and soldering. I'm not a pro, just sharing what worked for me.

AHA! That's exactly what I discovered with mine. I just assumed it was a bad repair. Good to know!!

I found several leaf switches riveted (or assembled) backwards; it's crazy that it took me 16 years to figure it out.

I'm pretty sure I used the smaller screw - I didn't want to have any screw pops.

No kidding, working switches are awesome!!

I can't believe millions of switches were assembled backwards...epic fail. Or perhaps a very devious kind of planned obsolescence.

Mof, several switches weren't registering reliably. It turns out the switch stacks were made incorrectly (with the contact facing the wrong way). Also, see my post #5 above. It's not really such a drastic change. The trough switches in the LE models were already microswitch-based. I just extended that improvement to all of the factory-borked switches.

I agree that if your switches were made correctly and they are registering reliably, this mod is not needed.

I tried that, and decided it was more hassle than it was worth. Purely a personal choice.

I’ll have to look at mine to see if I did those too. Unfortunately my BK is in storage at the moment.