Quoted from ectobar:
Looks like it's about 25 minutes away. So not bad, however, the only place worth going in Philly for pinball is the Barcade, which he can't get into.
PinballMap shows a couple locations close to Haddon with a couple pins each.
Hydman's Arcade is probably the best bet in NJ. Also about 20 minutes from Haddon Heights.
The best answer would be the Pinball Gallery in Malvern PA. It's about an hour from HH.
Will look into those.