So there was another thread that people debated on electrical contact cleaner. I contacted Stern technical support and they said "I have not tried this, but I think it should work."
I sent the below to Stern technical support:
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Hi, I bought a Metallica pro and I'm curious if I can use http://www.wd40specialist.com/products/contact-cleaner to clean the electronics in my pinball machine. Thanks!
Hi
I have not tried this, but I think it should work.
Best regards,
Stern Pinball Tech. Support
800 542-5377