Quoted from dri:Switches involved works just fine, I've changed diodes on the ramp exit and shooter lane (same row). Last time I had an issue like this on TZ I had to brute force it by changing every diode in the row and column of the affected switch.
This will only work 66.6% of the time as there is a 1 in 3 chance the problem is NOT in the same row or column as the phantom closure.
This type problem is one of the trickiest things to troubleshoot, having an oscilloscope does help with this one as there are specific timings involved, but the problem requires activation of 3 switches simultaneously to even be seen.
Take a look at this post https://pinside.com/pinball/forum/topic/gun-broken-and-suddenly-right-ramp-slam-tilt#post-4320824, its not for your specific machine but the principles still apply.
Quoted from dri:I'm chasing a credit dot on my DM.
Not sure what the credit dot is for since you didnt say, but a switch matrix phantom closure issue will not typically cause this as ALL switches will function normally.