I love these EM gun games too and someday when I have the space I'll own one. I seem to remember someone doing a solid state replacement for the analog tape unit, but I can't remember where I read it or if it was a mod or a one-off.
Quoted from Jimmydred:I have been looking for a haunted house shooter for sometime now...
There's one on eBay right now.
ebay.com link: Midway Haunted House Shooting Gallery Vintage Arcade