I had a similar issue with my Haunted House.
I borrowed a couple of (working fine) Homepin reproduction pop bumper boards from my System 80 Volcano machine, when getting Haunted House up and running.
Same thing as you, when switching on, pop bumpers would lock on. I quickly switched off.
I repaired and modified the original pop bumper boards, put them back in and all good now.
Put the Homepin ones back in Volcano and no problem either. Really weird

Do you still have the original pop bumper boards?

I was doing plenty of this trying to figure it out at the time. Odd thing is, I had a couple of the rottendog ones and they work fine in Haunted House.

Only reason I bought Homepin ones is because my Volcano had all pop boards missing and like I said, they work fine in Volcano.