Hi Aurich,
I am not sure if this is the same issue or not, but Chris Hibler came up with a fix for this some time back. See the thread URL below and the URL for the CH fix.
https://pinside.com/pinball/forum/topic/wh2o-lockup-popper-getting-stuck#post-1060390
http://webpages.charter.net/chibler/Pinball/Images/WH2OBackSpinFix.jpg
Gord