The stand-up/light-up targets use an opto. This could get dirty, or possibly weak.

Disassemble, clean the optos and reassemble. I use a q-tip with windex.

Right now it looks as though you can't buy part number A-20401

So don't break it!

Check the pins on the board to the connector soldering very carefully for cracked solder, you might want to reflow the connector while you have it apart.

It's not uncommon to have to replace the plug connector to these switches. The IDC type connectors can be shaken to the point they make intermittent connection.

If the phantom triggering persists, take one of the other stand-up/light-up targets and switch places. If the problem follows, you've got a problem on the original target. If the problem persists in the same way with a different target, you've got a wiring problem or possibly a switch matrix problem.

Let us know what you find!

Good catch! For US buyers Pinball Center will not directly ship to the USA, so it's a little harder for us to get these parts than it is for you in Alberta Canada.

Pinside user Zitt has made truly heroic effort to arrange parts shipping from Pinball Center, here is his thread, for anyone who needs parts that only Pinball Center has.

https://pinside.com/pinball/forum/topic/pinballcenter-parts-needed