Shaker motors are totally safe for both electronics and cabinet.
EVERY old game has various parts in the bottom of the cab before it's restored, it's not like Earthshaker is unique in that respect.
Newer electronic components are much lighter weight and thus less likely to crack their solder joints from the mass's momentum.
Ghosting is the failure of the clearcoat to adhere to the substrate.
The clearcoat does not peel off those giant subwoofers in your theater, and they run continuously.